ThZeal - The Zeal

Global Life Sciences Fund

[JANUS HENDERSON LOGO]

Janus Henderson Global Life Sciences Fund

Ticker:	JFNAX	Class A Shares	JFNSX	Class S Shares	JFNNX	Class N Shares
	JFNCX	Class C Shares	JFNIX	Class I Shares	JAGLX	Class T Shares

Summary Prospectus dated January 26, 2024

Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus, reports to shareholders, and other information about the Fund online at janushenderson.com/info. You can also get this information at no cost by calling a Janus Henderson representative at 1-877-335-2687 or by sending an email request to prospectusrequest@janushenderson.com.

Investment Objective

Janus Henderson Global Life Sciences Fund seeks long-term growth of capital.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy, hold, and sell Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund. For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus Henderson funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 128 of the Fund’s Prospectus and in the “Purchases” section on page 77 of the Fund’s Statement of Additional Information. In addition, please see Appendix A – Intermediary Sales Charge Waivers and Discounts. You may also incur brokerage commissions charged by your broker or financial intermediary when buying Class I Shares or Class N Shares of the Fund that are not reflected in the table or in the example below.

SHAREHOLDER FEES (fees paid directly from your investment)	Class A	Class C	Class S	Class I	Class N	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	None	None	None	None	None
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	None	1.00%	None	None	None	None
ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class S	Class I	Class N	Class T
Management Fees	0.64%	0.64%	0.64%	0.64%	0.64%	0.64%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	None	None	None
Other Expenses	0.09%	0.12%	0.29%	0.13%	0.03%	0.28%
Total Annual Fund Operating Expenses	0.98%	1.76%	1.18%	0.77%	0.67%	0.92%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Class C Shares automatically convert to Class A Shares after eight years. The Example for Class C Shares for the ten-year period reflects the conversion to Class A Shares. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:	1 Year	3 Years	5 Years	10 Years
Class A Shares	$669	$869	$1,086	$1,707
Class C Shares	$279	$554	$954	$1,867
Class S Shares	$120	$375	$649	$1,432
Class I Shares	$79	$246	$428	$954
Class N Shares	$68	$214	$373	$835
Class T Shares	$94	$293	$509	$1,131

1 | Janus Henderson Global Life Sciences Fund

If Shares are not redeemed:	1 Year	3 Years	5 Years	10 Years
Class A Shares	$669	$869	$1,086	$1,707
Class C Shares	$179	$554	$954	$1,867
Class S Shares	$120	$375	$649	$1,432
Class I Shares	$79	$246	$428	$954
Class N Shares	$68	$214	$373	$835
Class T Shares	$94	$293	$509	$1,131

Portfolio Turnover: The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 34% of the average value of its portfolio.

Principal investment strategies

The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in securities of companies that portfolio management believes have a life science orientation. In the Fund’s pursuit of companies with a life science orientation, the Fund has a fundamental policy to normally invest at least 25% of its total assets in securities of companies that are categorized in the “life sciences” sector, which may include companies in the following industry groups: pharmaceuticals; biotechnology; health care services; agriculture; cosmetics/personal care; and medical devices. Generally speaking, the “life sciences” relate to maintaining or improving quality of life. So, for example, companies with a “life science orientation” include companies engaged in research, development, production, or distribution of products or services related to health and personal care, medicine, or pharmaceuticals. The Fund implements its investment policies by investing primarily in equity securities of U.S. and foreign companies selected for their growth potential. The Fund normally invests in issuers from several different countries, which may include the United States. An issuer is deemed to be economically tied to a country or countries if one or more of the following tests are met: (i) the issuer is organized in, or its primary business office or principal trading market of its equity is located in, the country; (ii) a majority of the issuer’s revenues are derived from one or more countries; or (iii) a majority of the issuer’s assets are located in one or more countries. The Fund may, under unusual circumstances, invest in a single country. The Fund may invest in shares of companies through initial public offerings and private placements.

Portfolio management applies a “bottom up” approach in choosing investments. In other words, portfolio management looks at companies one at a time to determine if a company is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. In conducting the “bottom up” analysis, portfolio management considers factors including a company’s growth potential, the strength of a company’s management, and a company’s sustainable competitive advantages, returns on investment capital, and cash flow generation. Portfolio management also applies screens, which incorporate third-party inputs, to (i) seek to avoid investing in issuers that are United Nations Global Compact violators and (ii) seek to invest at least 80% of the Fund’s net assets, under normal circumstances, in issuers with an MSCI (or an equivalent third-party data provider, as determined by portfolio management) ESG rating of BB or higher.

The Fund will generally consider selling a stock when, in portfolio management’s opinion, the stock shows declining fundamentals, its competitive advantages have deteriorated, or if the stock reaches its targeted value. The Fund will also consider selling a stock if, in portfolio management’s opinion, a superior investment opportunity arises.

The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions on a short-term or long-term basis, in an amount equal to up to one-third of its total assets as determined at the time of the loan origination.

Principal investment risks

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. The principal risks associated with investing in the Fund are set forth below.

2 | Janus Investment Fund

Market Risk. The value of the Fund’s portfolio may decrease due to short-term market movements and over more prolonged market downturns. As a result, the Fund’s net asset value may fluctuate and it may be more difficult to value or sell the Fund’s holdings. Market risk may affect a single issuer, industry, economic sector, or the market as a whole. Market risk may be magnified if certain social, political, economic, and other conditions and events (such as terrorism, conflicts, including related sanctions, social unrest, natural disasters, epidemics and pandemics, including COVID-19) adversely interrupt the global economy and financial markets. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Small- and Mid-Sized Companies Risk. Investments in securities issued by small- and mid-sized companies, which can include smaller, start-up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. For example, small- and mid-sized companies may suffer more significant losses as a result of their narrow product lines, limited operating history, greater exposure to competitive threats, limited financial resources, limited trading markets, and the potential lack of management depth. Securities issued by small- and mid-sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger or more established companies. These holdings are also subject to wider price fluctuations and tend to be less liquid than stocks of larger or more established companies, which could have a significant adverse effect on the Fund’s returns, especially as market conditions change.

Growth Securities Risk. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If portfolio management’s perception of a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from other types of securities and the market as a whole.

Industry and Sector Risk. The Fund may have a significant portion of its assets invested in securities of companies conducting similar business or businesses within the same economic sector. Companies in the same industry or economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments than funds that invest more broadly. As the Fund’s portfolio becomes more concentrated, the Fund is less able to spread risk and potentially reduce the risk of loss and volatility. In addition, the Fund may be overweight or underweight in certain industries or sectors relative to its benchmark index, which may cause the Fund’s performance to be more or less sensitive to developments affecting those sectors.

•

Life Sciences Sector Risk. The Fund focuses its investments in securities of companies that are categorized in the “life sciences” sector, including companies in the following industry groups: pharmaceuticals, biotechnology, health care services, agriculture, cosmetic/personal care, and medical devices. Because of this, companies in the Fund’s portfolio may share common characteristics and may be more sensitive to changes in government funding or subsidies, new or anticipated legislative changes, or technological advances.

Initial Public Offering Risk. The Fund’s purchase of shares issued in an initial public offering (“IPO”) exposes it to the risks associated with companies that have little operating history as public companies, as well as to the risks inherent in those sectors of the market where these new issuers operate. There can be no assurance that the Fund will identify favorable IPO investment opportunities.

ESG Investment Risk. Because the Fund considers environmental, social, and governance (“ESG”) factors in selecting securities, the Fund may perform differently than funds that do not consider ESG factors. Due to the ESG considerations and exclusionary criteria employed by the Fund, the Fund may not be invested in certain issuers, and therefore may have lower performance than portfolios that do not apply similar criteria. ESG-related information provided by issuers and third parties, which portfolio management may utilize, continues to develop, and may be incomplete, inaccurate, use different methodologies, or be applied differently across companies and industries. Further, the regulatory landscape for ESG investing in the United States is still developing and future rules and regulations may require the Fund to modify or alter its investment process. Similarly, government policies incentivizing companies to consider their environmental or social practices may fall out of favor, which could potentially limit the Fund’s investment universe. There is also a risk that the issuers identified through the investment process employed by the Fund may fail to adhere to positive environmental or social practices, which may result in selling a security when it might otherwise be disadvantageous to do so.

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Portfolio Management Risk. The Fund is an actively managed investment portfolio and is therefore subject to the risk that the investment strategies and research process employed for the Fund may fail to produce the intended results. Accordingly, the Fund may underperform its benchmark index or other mutual funds with similar investment objectives.

Geographic Concentration Risk. To the extent the Fund invests a substantial amount of its assets in issuers located in a single country or region, the economic, political, social, regulatory, or other developments or conditions within such country or region will generally have a greater effect on the Fund than they would on a more geographically diversified fund, which may result in greater losses and volatility. Adverse developments in certain regions could also adversely affect securities of other countries whose economies appear to be unrelated and could have a negative impact on the Fund’s performance.

Liquidity Risk. The Fund may invest in securities or instruments that do not trade actively or in large volumes, and may make investments that are less liquid than other investments. Also, the Fund may make investments that may become less liquid in response to market developments or adverse investor perceptions. Investments that are illiquid or that trade in lower volumes may be more difficult to value. When there is no willing buyer and investments cannot be readily sold at the desired time or price, the Fund may have to accept a lower price or may not be able to sell the security or instrument at all. Investments in foreign securities, particularly those of issuers located in emerging market countries, tend to have greater exposure to liquidity risk than domestic securities. In unusual market conditions, even normally liquid securities may be affected by a degree of liquidity risk (i.e., if the number and capacity of traditional market participants is reduced). An inability to sell one or more portfolio positions can adversely affect the Fund’s value or prevent the Fund from being able to take advantage of other investment opportunities.

Private Placements Risk. Investments in private placements could decrease the Fund’s liquidity profile or prevent the Fund from disposing of such securities promptly at advantageous prices. Private placements may be less liquid than other investments because such securities may not always be readily sold in broad public markets and may have no active trading market. As a result, they may be difficult to value because market quotations may not be readily available, and the Fund might be unable to dispose of such securities promptly or at prices reflecting their true value. Transaction costs may be higher for these securities, and the Fund may get only limited information about the issuer of a private placement security, so it may be less able to anticipate a loss.

Securities Lending Risk. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

Foreign Exposure Risk. Foreign markets can be more volatile than the U.S. market. As a result, the Fund’s returns and net asset value may be affected by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. The Fund’s investments may also be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance information

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on January 26, 2018.

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The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.

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The performance shown for Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.

•

The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.

•

The performance shown for Class N Shares for periods prior to January 26, 2018, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during the periods prior to July 6, 2009 or Class N Shares of the Fund had been available during periods prior to January 26, 2018, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class N Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index, as well as to one or more supplemental indices that have investment characteristics similar to those of the Fund. All figures assume reinvestment of dividends and distributions.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janushenderson.com/performance or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:

2nd Quarter 2020

21.01%

Worst Quarter:

1st Quarter 2020

– 13.67%

Average Annual Total Returns (periods ended 12/31/23)
	1 Year	5 Years	10 Years	Since Inception (12/31/98)
Class T Shares
Return Before Taxes	7.40%	12.52%	11.40%	11.25%
Return After Taxes on Distributions	6.31%	10.96%	9.65%	10.42%
Return After Taxes on Distributions and Sale of Fund Shares	5.08%	9.74%	8.87%	9.78%
MSCI World Health Care Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	3.76%	10.47%	9.01%	6.72%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	7.56%

5 | Janus Henderson Global Life Sciences Fund

Average Annual Total Returns (periods ended 12/31/23)
	1 Year	5 Years	10 Years	Since Inception (12/31/98)
Class A Shares
Return Before Taxes(1)	1.13%	11.11%	10.65%	10.86%
MSCI World Health Care Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	3.76%	10.47%	9.01%	6.72%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	7.56%
Class C Shares
Return Before Taxes(2)	5.49%	11.64%	10.49%	10.31%
MSCI World Health Care Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	3.76%	10.47%	9.01%	6.72%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	7.56%
Class S Shares
Return Before Taxes	7.10%	12.21%	11.12%	10.95%
MSCI World Health Care Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	3.76%	10.47%	9.01%	6.72%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	7.56%
Class I Shares
Return Before Taxes	7.54%	12.68%	11.56%	11.34%
MSCI World Health Care Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	3.76%	10.47%	9.01%	6.72%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	7.56%
Class N Shares
Return Before Taxes	7.64%	12.78%	11.55%	11.31%
MSCI World Health Care Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	3.76%	10.47%	9.01%	6.72%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	7.56%

(1)

Calculated assuming maximum permitted sales loads.

(2)

The one year return is calculated to include the contingent deferred sales charge.

The Fund’s primary benchmark index is the MSCI World Health Care Index. The Fund also compares its performance to the S&P 500 Index. The indices are described below.

•

The MSCI World Health Care Index is a capitalization-weighted index that measures the performance of health care stocks from developed market countries.

•

The S&P 500 Index is a commonly recognized, market capitalization-weighted index of 500 widely held equity securities, designed to measure broad U.S. equity performance.

After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ

6 | Janus Investment Fund

from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

Management

Investment Adviser: Janus Henderson Investors US LLC

Portfolio Management: Andy Acker, CFA, is Executive Vice President and Lead Portfolio Manager of the Fund, which he has managed or co-managed since May 2007. Daniel Lyons, Ph.D., CFA, is Executive Vice President and Co-Portfolio Manager of the Fund, which he has co-managed since January 2023.

Purchase and sale of Fund shares

Minimum Investment Requirements

Class A Shares, Class C Shares*, Class S Shares, and Class T Shares
Non-retirement accounts	$2,500**
Certain tax-advantaged accounts or UGMA/UTMA accounts	$500
Class I Shares
Institutional investors (investing directly with the Fund)	$1,000,000
Through an intermediary institution
• non-retirement accounts	$2,500 †
• certain tax-advantaged accounts or UGMA/UTMA accounts	$500 †
Class N Shares
Retirement investors (investing through an adviser-assisted, employer-sponsored retirement plan)	None
Retail investors (investing through a financial intermediary omnibus account)	$2,500***
Institutional investors (investing directly with the Fund)	$1,000,000

†

Exceptions to these minimums may apply for certain tax-advantaged, tax-qualified and retirement plans, including health savings accounts, accounts held through certain wrap programs, and certain retail brokerage accounts.

The maximum purchase in Class C Shares is $500,000 for any single purchase.

Class A, Class C, Class S, and Class T shares held through certain supermarket and/or self-directed brokerage accounts, or through wrap programs, may not be subject to these minimums. Please contact your financial intermediary for more information.

***

Investors in certain tax-advantaged accounts or accounts held through certain wrap programs or bank trust platforms may not be subject to this minimum.

Purchases, exchanges, and redemptions can generally be made only through institutional channels, such as financial intermediaries and retirement platforms. Class I Shares may be purchased directly by certain institutional investors who established Class I Shares accounts before August 4, 2017. You should contact your financial intermediary or refer to your plan documents for information on how to invest in the Fund. Requests must be received in good order by the Fund or its agents (financial intermediary or plan sponsor, if applicable) prior to the close of the trading session of the New York Stock Exchange in order to receive that day’s net asset value. For additional information, refer to “Purchases,” “Exchanges,” and/or “Redemptions” in the Prospectus.

Tax information

The Fund’s distributions are taxable, and will be taxed as ordinary income or capital gains, unless you are investing through a tax-advantaged arrangement, such as a 401(k) plan or an individual retirement account (in which case you may be taxed upon withdrawal of your investment from such account).

7 | Janus Henderson Global Life Sciences Fund

Payments to broker-dealers and other financial intermediaries

If you purchase Class A Shares, Class C Shares, Class S Shares, Class I Shares, or Class T Shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund or its distributor (or its affiliates) may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment or to recommend one share class over another. There is some regulatory uncertainty concerning whether marketing support or other similar payments may be made or received in connection with Class I Shares where a financial intermediary has imposed its own sales charges or transaction fees. As a result, based on future regulatory developments, such payments may be terminated, or the Fund may prohibit financial intermediaries from imposing such sales charges or transaction fees in connection with Class I Shares. Ask your salesperson or visit your financial intermediary’s website for more information.

8 | Janus Investment Fund

[JANUS HENDERSON LOGO]

Janus Henderson Global Life Sciences Fund

Ticker:

JNGLX

Class D Shares

Summary Prospectus dated January 26, 2024

Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus, reports to shareholders, and other information about the Fund online at janushenderson.com/reports. You can also get this information at no cost by calling a Janus Henderson representative at 1-800-525-3713 or by sending an email request to prospectusorder@janushenderson.com.

Investment Objective

Janus Henderson Global Life Sciences Fund seeks long-term growth of capital.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy, hold, and sell Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)		Class D
Management Fees		0.64%
Other Expenses		0.16%
Total Annual Fund Operating Expenses		0.80%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

	1 Year	3 Years	5 Years	10 Years
Class D Shares	$82	$255	$444	$990

Principal investment strategies

1 | Janus Henderson Global Life Sciences Fund

Principal investment risks

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2 | Janus Investment Fund

agriculture, cosmetic/personal care, and medical devices. Because of this, companies in the Fund’s portfolio may share common characteristics and may be more sensitive to changes in government funding or subsidies, new or anticipated legislative changes, or technological advances.

3 | Janus Henderson Global Life Sciences Fund

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance information

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for the periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index, as well as to one or more supplemental indices that have investment characteristics similar to those of the Fund. All figures assume reinvestment of dividends and distributions.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:

2nd Quarter 2020

21.04%

Worst Quarter:

1st Quarter 2020

– 13.64%

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Average Annual Total Returns (periods ended 12/31/23)
	1 Year	5 Years	10 Years	Since Inception (12/31/98)
Class D Shares
Return Before Taxes	7.50%	12.63%	11.51%	11.30%
Return After Taxes on Distributions	6.40%	11.05%	9.74%	10.47%
Return After Taxes on Distributions and Sale of Fund Shares	5.15%	9.82%	8.95%	9.82%
MSCI World Health Care Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	3.76%	10.47%	9.01%	6.72%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	7.56%

The Fund’s primary benchmark index is the MSCI World Health Care Index. The Fund also compares its performance to the S&P 500 Index. The indices are described below.

•

The MSCI World Health Care Index is a capitalization-weighted index that measures the performance of health care stocks from developed market countries.

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The S&P 500 Index is a commonly recognized, market capitalization-weighted index of 500 widely held equity securities, designed to measure broad U.S. equity performance.

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.

Management

Investment Adviser: Janus Henderson Investors US LLC

Purchase and sale of Fund shares

Minimum Investment Requirements
To open a new regular Fund account	$2,500
To open a new regular Fund account with an automatic investment program of $50 per month	$100
To open a new UGMA/UTMA account, Coverdell Education Savings Account, or a retirement Fund account
• without an automatic investment program	$1,000
• with an automatic investment program of $50 per month	$100
To add to any existing type of Fund account without an automatic investment program	$50

You may generally purchase, exchange, or redeem Fund Shares on any business day by written request, wire transfer, telephone, and in most cases, online at janushenderson.com/individual. You may conduct transactions by mail (Janus Henderson, P.O. Box 219109, Kansas City, MO 64121-9109), or by telephone at 1-800-525-3713. Purchase, exchange, or redemption requests must be received in good order by the Fund or its agents prior to the close of the trading session of the New York Stock Exchange in order to receive that day’s net asset value. For additional information, refer to “To Open an Account or Buy Shares,” “To Exchange Shares,” and/or “To Sell Shares” in the Prospectus.

5 | Janus Henderson Global Life Sciences Fund

Tax information

Payments to broker-dealers and other financial intermediaries

With respect to share classes not offered in this Prospectus, the Fund or its distributor (or its affiliates) pay select broker-dealer firms or other financial intermediaries for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing a broker-dealer or other intermediary or a salesperson to recommend the Fund over another investment or to recommend one share class over another.

6 | Janus Investment Fund