June 2, 2025

Prospectus Supplement

SUPPLEMENT DATED JUNE 2, 2025 to the PROSPECTUSES OF

Morgan Stanley Europe Opportunity Fund, Inc., dated February 28, 2025, as supplemented
Morgan Stanley Income Opportunities Fund, dated February 28, 2025, as amended May 30, 2025
Morgan Stanley Insight Fund, dated April 30, 2025
Morgan Stanley Long Duration Government Opportunities Fund, dated April 30, 2025
Morgan Stanley Mortgage Securities Trust, dated February 28, 2025, as supplemented

Effective immediately, the following is hereby added to the end of the section of each Prospectus titled "Appendix A—Intermediary-Specific Sales Charge Waivers and Discounts":

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Wells Fargo Advisors Financial Network, LLC (collectively, "Wells Fargo Advisors")

Wells Fargo Clearing Services, LLC operates a First Clearing business, but these rules are not intended to include First Clearing firms.

Effective October 1, 2025, Clients of Wells Fargo Advisors purchasing fund shares through Wells Fargo Advisors are eligible for the following sales charge discounts (also referred to as "breakpoints") and waivers, which can differ from discounts and waivers described elsewhere in the prospectus or statement of additional information ("SAI"). In all instances, it is the investor's responsibility to inform Wells Fargo Advisors at the time of purchase of any relationship, holdings, or other facts qualifying the investor for discounts or waivers. Wells Fargo Advisors can ask for documentation supporting the qualification.

Wells Fargo Advisors Class A share front-end sales charge waivers information.

Wells Fargo Advisors clients purchasing or converting to Class A shares of the fund in a Wells Fargo Advisors brokerage account are entitled to a waiver of the front-end load in the following circumstances:

•  Wells Fargo Advisors employee and employee-related accounts according to Wells Fargo Advisor's employee account linking rules. Legacy accounts and positions receiving affiliate discounts prior to the effective date will continue to receive discounts. Going forward employees of affiliate businesses will not be offered NAV.

•  Shares purchased through reinvestment of dividends and capital gains distributions when purchasing shares of the same fund.

WellsTrade, the firm's online self-directed brokerage account, generally offers no-load share classes but there could be instances where a Class A share is offered without a front-end sales charge.

Wells Fargo Advisors Class 529-A share front-end sales charge waivers information.

Wells Fargo Advisors clients purchasing or converting to Class 529-A shares of the fund through Wells Fargo Advisors transactional brokerage accounts are entitled to a waiver of the front-end load in the following circumstances:

•  Shares purchased through a rollover from another 529 plan.

•  Recontribution(s) of distributed funds are only allowed during the NAV reinstatement period as dictated by the sponsor's specifications outlined by the plan.

Wells Fargo Advisors is not able to apply the NAV Reinstatement privilege for 529 Plan account purchases placed directly at the fund company. Investors wishing to utilize this privilege outside of Wells Fargo systems will need to do so directly with the Plan or a financial intermediary that supports this feature.

Unless specifically described above, other front-end load waivers are not available on mutual fund purchases through Wells Fargo Advisors.

Wells Fargo Advisors Contingent Deferred Sales Charge information.

•  Contingent deferred sales charges (CDSC) imposed on fund redemptions will not be rebated based on future purchases.

Wells Fargo Advisors Class A front-end load discounts

Wells Fargo Advisors Clients purchasing Class A shares of the fund through Wells Fargo Advisors brokerage accounts will follow the following aggregation rules for breakpoint discounts:

•  As of the effective date, SEP or SIMPLE IRAs will not be aggregated as a group plan. They will aggregate with the client's personal accounts based on Social Security Number. Previously established SEP and SIMPLE IRAs may still be aggregated as a group plan.

•  Effective October 1, 2025, Employer-sponsored retirement plan (e.g., 401(k) plans, 457 plans, employer-sponsored 403(b) plans, profit sharing and money purchase pension plans and defined benefit plans). For purposes of this provision, employer-sponsored retirement plans do not include SEP IRAs, SIMPLE IRAs, SAR-SEPs or Keogh plans.

•  Gift of shares will not be considered when determining breakpoint discounts.

Please retain this supplement for future reference.

MSPROSPT 6/25