ThZeal - The Zeal

Research Fund

[JANUS HENDERSON LOGO]

Janus Henderson Research Fund

Ticker:	JRAAX	Class A Shares	JRASX	Class S Shares	JRANX	Class N Shares	JAMRX	Class T Shares
	JRACX	Class C Shares	JRAIX	Class I Shares	JRARX	Class R 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 Research 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 102 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 R	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	None	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	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 R	Class T
Management Fees(1)	0.48%	0.48%	0.48%	0.48%	0.48%	0.48%	0.48%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	None	None	0.50%	None
Other Expenses	0.08%	0.14%	0.28%	0.09%	0.01%	0.35%	0.26%
Total Annual Fund Operating Expenses	0.81%	1.62%	1.01%	0.57%	0.49%	1.33%	0.74%
Fee Waiver and/or Expense Reimbursement(2)	0.00%	0.01%	0.00%	0.00%	0.00%	0.06%	0.00%
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement(2)	0.81%	1.61%	1.01%	0.57%	0.49%	1.27%	0.74%

(1)

This fee may adjust up or down monthly based on the Fund’s performance relative to its benchmark index over the performance measurement period. For more information regarding performance-based advisory fees, refer to “Management Expenses” in the Fund’s Prospectus.

(2)

The Adviser has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus fees payable by any share class, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.68% for at least a one-year period commencing on January 26, 2024. This contractual waiver may be terminated or modified only at the discretion of the Board of Trustees.

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 are equal to the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and the Total Annual Fund Operating Expenses thereafter. Class C Shares automatically convert to Class A Shares

1 | Janus Henderson Research Fund

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	$653	$819	$999	$1,519
Class C Shares	$264	$510	$880	$1,763
Class S Shares	$103	$322	$558	$1,236
Class I Shares	$58	$183	$318	$714
Class N Shares	$50	$157	$274	$616
Class R Shares	$129	$416	$723	$1,596
Class T Shares	$76	$237	$411	$918

If Shares are not redeemed:	1 Year	3 Years	5 Years	10 Years
Class A Shares	$653	$819	$999	$1,519
Class C Shares	$164	$510	$880	$1,763
Class S Shares	$103	$322	$558	$1,236
Class I Shares	$58	$183	$318	$714
Class N Shares	$50	$157	$274	$616
Class R Shares	$129	$416	$723	$1,596
Class T Shares	$76	$237	$411	$918

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 27% of the average value of its portfolio.

Principal investment strategies

The Fund pursues its investment objective by investing primarily in common stocks selected for their growth potential. The Fund may invest in companies of any size, from larger, well-established companies to smaller, emerging growth companies.

The Adviser’s equity research analysts (the “Central Research Team”) select investments for the Fund that represent the Central Research Team’s high-conviction investment ideas in all market capitalizations and styles. The Central Research Team conducts fundamental analysis with a focus on “bottom up” research, quantitative modeling, and valuation analysis. Using this research process, analysts rate their stocks based upon attractiveness. Stocks considered to be attractive may have all or some of the following characteristics: (i) good and preferably growing free cash flow, (ii) strong and defensible market position, (iii) healthy risk/return profile, (iv) exemplary governance, and (v) attractive valuation. Analysts bring their high-conviction ideas to their respective sector teams. Each sector team compares the appreciation and risk potential of its high-conviction ideas and constructs a sector sleeve that is intended to maximize the best risk-reward opportunities. The sector sleeves are then combined to form the Fund’s overall portfolio. The Portfolio Oversight Team, which includes portfolio management, oversees the overall portfolio to manage unintended style risks. Although the Central Research Team may find high-conviction investment ideas anywhere in the world, the Central Research Team emphasizes investments in securities of U.S.-based issuers for this Fund.

Positions may be sold when, among other things, there is no longer high conviction in the return potential of the investment, if the risk characteristics have caused a re-evaluation of the opportunity, or if the investment thesis for owning a position has changed. This may occur if the stock has appreciated and reflects the anticipated value, if another company represents a better risk-reward opportunity, or if the investment’s fundamental characteristics deteriorate. Securities may also be sold from the portfolio to rebalance sector weightings.

2 | Janus Investment Fund

to be fully invested under normal circumstances. However, under unusual circumstances, if the Central Research Team does not have high conviction in enough investment opportunities, the Fund’s uninvested assets may be held in cash or similar instruments.

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.

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.

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. The Fund’s Central Research Team compares and broadly matches the Fund’s sector weights to those of a growth-based index. If growth stocks are out of favor, sectors that are larger in a growth index may underperform, leading to Fund underperformance relative to indices less biased toward growth stocks.

Industry and Sector Risk. Although the Fund does not concentrate its investments in specific industries, it 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.

Mid-Sized Companies Risk. Investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. For example, 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 mid-sized companies tend to be more volatile 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.

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.

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.

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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 May 31, 2012. Class R Shares of the Fund commenced operations on January 27, 2017.

•

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.

•

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 May 31, 2012, 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.

•

The performance shown for Class R Shares for periods prior to January 27, 2017, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class R Shares, without the effect of any 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 periods prior to July 6, 2009, Class N Shares of the Fund had been available during periods prior to May 31, 2012, or Class R Shares of the Fund had been available during periods prior to January 27, 2017, the performance shown for each respective share class may have been different. The performance shown for the periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R 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. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

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.

4 | Janus Investment Fund

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

Best Quarter:

2nd Quarter 2020

26.71%

Worst Quarter:

2nd Quarter 2022

– 22.33%

Average Annual Total Returns (periods ended 12/31/23)
	1 Year	5 Years	10 Years	Since Inception (5/3/93)
Class T Shares
Return Before Taxes	42.96%	16.64%	12.40%	11.59%
Return After Taxes on Distributions	41.97%	15.10%	10.45%	10.16%
Return After Taxes on Distributions and Sale of Fund Shares	26.09%	13.25%	9.65%	9.68%
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)	42.68%	19.50%	14.86%	10.60%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	10.18%
Class A Shares
Return Before Taxes(1)	34.61%	15.16%	11.62%	11.19%
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)	42.68%	19.50%	14.86%	10.60%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	10.18%
Class C Shares
Return Before Taxes(2)	40.98%	15.73%	11.50%	10.63%
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)	42.68%	19.50%	14.86%	10.60%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	10.18%
Class S Shares
Return Before Taxes	42.56%	16.31%	12.10%	11.24%
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)	42.68%	19.50%	14.86%	10.60%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	10.18%
Class I Shares
Return Before Taxes	43.14%	16.81%	12.57%	11.67%
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)	42.68%	19.50%	14.86%	10.60%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	10.18%

5 | Janus Henderson Research Fund

Average Annual Total Returns (periods ended 12/31/23)
	1 Year	5 Years	10 Years	Since Inception (5/3/93)
Class N Shares
Return Before Taxes	43.27%	16.90%	12.67%	11.69%
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)	42.68%	19.50%	14.86%	10.60%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	10.18%
Class R Shares
Return Before Taxes	42.19%	16.01%	11.83%	11.09%
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)	42.68%	19.50%	14.86%	10.60%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	10.18%

(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 Russell 1000 Growth Index. The Fund also compares its performance to the S&P 500 Index. The indices are described below.

•

The Russell 1000 Growth Index measures the performance of those Russell 1000 companies with higher price-to-book ratios and higher forecasted growth values.

•

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 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: Joshua Cummings, John Jordan, and Matthew Peron oversee the investment process and are primarily responsible for the day-to-day management of the Fund. Joshua Cummings, CFA, is Co-Portfolio Manager of the Fund, which he has co-managed since January 2024. John Jordan is Co-Portfolio Manager of the Fund, which he has co-managed since January 2024. Matthew Peron is Executive Vice President and Co-Portfolio Manager of the Fund, which he has managed or co-managed since April 2020.

Mr. Peron will be stepping down as Executive Vice President and Co-Portfolio Manager of the Fund effective September 30, 2024, but will remain in these roles until that time to assist in transitioning the Fund.

6 | Janus Investment Fund

Purchase and sale of Fund shares

Minimum Investment Requirements

Class A Shares, Class C Shares*, Class S Shares, Class R 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. For Class R shareholders, there is no investment minimum for defined contribution plans. Investors in a defined contribution plan through a third party administrator should refer to their plan document or contact their plan administrator for additional information regarding account minimums.

***

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).

Payments to broker-dealers and other financial intermediaries

If you purchase Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class R 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.

7 | Janus Henderson Research Fund

[JANUS HENDERSON LOGO]

Janus Henderson Research Fund

Ticker:

JNRFX

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 Research 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(1)		0.48%
Other Expenses		0.14%
Total Annual Fund Operating Expenses		0.62%

(1)

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	$63	$199	$346	$774

Principal investment strategies

1 | Janus Henderson Research Fund

The Fund’s portfolio management, which includes two analysts on the Central Research Team, oversees the investment process and is responsible for the day-to-day management of the Fund. Although the Fund’s exposure to certain sectors may be higher than to others, it is expected that the Fund will be broadly diversified among a variety of sectors. The Fund intends to be fully invested under normal circumstances. However, under unusual circumstances, if the Central Research Team does not have high conviction in enough investment opportunities, the Fund’s uninvested assets may be held in cash or similar instruments.

Principal investment risks

2 | Janus Investment 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. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

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

Best Quarter:

2nd Quarter 2020

26.75%

Worst Quarter:

2nd Quarter 2022

– 22.31%

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Average Annual Total Returns (periods ended 12/31/23)
	1 Year	5 Years	10 Years	Since Inception (5/3/93)
Class D Shares
Return Before Taxes	43.08%	16.75%	12.50%	11.64%
Return After Taxes on Distributions	42.08%	15.19%	10.52%	10.20%
Return After Taxes on Distributions and Sale of Fund Shares	26.17%	13.34%	9.72%	9.71%
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)	42.68%	19.50%	14.86%	10.60%
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)	26.29%	15.69%	12.03%	10.18%

The Fund’s primary benchmark index is the Russell 1000 Growth Index. The Fund also compares its performance to the S&P 500 Index. The indices are described below.

•

The Russell 1000 Growth Index measures the performance of those Russell 1000 companies with higher price-to-book ratios and higher forecasted growth values.

•

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

4 | Janus Investment Fund

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.

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.

5 | Janus Henderson Research Fund