Flexible Bond Fund

[JANUS HENDERSON LOGO]

Janus Henderson Flexible Bond Fund

Ticker:	JDFAX	Class A Shares	JADFX	Class S Shares	JDFNX	Class N Shares	JAFIX	Class T Shares
	JFICX	Class C Shares	JFLEX	Class I Shares	JDFRX	Class R Shares

Summary Prospectus dated October 28, 2022

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 Flexible Bond Fund seeks to obtain maximum total return, consistent with preservation 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 103 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)	4.75%	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	0.41%	0.41%	0.41%	0.41%	0.41%	0.41%	0.41%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	None	None	0.50%	None
Other Expenses	0.19%	0.10%	0.29%	0.10%	0.02%	0.28%	0.27%
Total Annual Fund Operating Expenses	0.85%	1.51%	0.95%	0.51%	0.43%	1.19%	0.68%
Fee Waiver(1)	0.15%	0.06%	0.00%	0.06%	0.00%	0.00%	0.00%
Total Annual Fund Operating Expenses After Fee Waiver(1)	0.70%	1.45%	0.95%	0.45%	0.43%	1.19%	0.68%

(1)

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 the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (but excluding out-of-pocket costs); brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.45% for at least a one-year period commencing on October 28, 2022. 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 for the first year and the Total Annual Fund Operating Expenses thereafter. Class C Shares automatically convert to Class A Shares after eight years. The Example

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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	$ 543	$ 719	$ 910	$ 1,461
Class C Shares	$ 248	$ 471	$ 818	$ 1,618
Class S Shares	$ 97	$ 303	$ 525	$ 1,166
Class I Shares	$ 46	$ 158	$ 279	$ 635
Class N Shares	$ 44	$ 138	$ 241	$ 542
Class R Shares	$ 121	$ 378	$ 654	$ 1,443
Class T Shares	$ 69	$ 218	$ 379	$ 847

If Shares are not redeemed:	1 Year	3 Years	5 Years	10 Years
Class A Shares	$ 543	$ 719	$ 910	$ 1,461
Class C Shares	$ 148	$ 471	$ 818	$ 1,618
Class S Shares	$ 97	$ 303	$ 525	$ 1,166
Class I Shares	$ 46	$ 158	$ 279	$ 635
Class N Shares	$ 44	$ 138	$ 241	$ 542
Class R Shares	$ 121	$ 378	$ 654	$ 1,443
Class T Shares	$ 69	$ 218	$ 379	$ 847

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 158% of the average value of its portfolio.

Principal investment strategies

The Fund pursues its investment objective by primarily investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in bonds. Bonds include, but are not limited to, government notes and bonds, corporate bonds, commercial and residential mortgage-backed securities, asset-backed securities, credit risk transfer securities (“CRTs”), and money market instruments. The Fund may invest in fixed and floating rate obligations with varying durations. The Fund’s average portfolio duration typically ranges between three and seven years. As of June 30, 2022, the Fund’s average portfolio duration was 6.17 years.

The Fund will invest at least 65% of its net assets in investment grade debt securities. The Fund will limit its investment in high-yield/high-risk bonds (also known as “junk” bonds) to 35% or less of its net assets. The Fund generates total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund may enter into “to be announced” or “TBA” commitments when purchasing mortgage-backed securities or other securities. The Fund may also invest in securities that cannot be offered for public resale unless registered under the applicable securities laws or that have a contractual restriction that prohibits or limits their resale (these are known as “restricted securities”), which may include Rule 144A securities. The Fund may also invest in foreign securities, which may include investments in emerging market securities. Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

Additionally, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate swaps and futures, including Treasury bond futures, to manage interest rate risk, yield curve positioning, and country exposure. The Fund may also use index credit default swaps for hedging purposes (to offset risks associated with an investment exposure, or market conditions), to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund relative to its benchmark index, and to earn income, enhance returns, or preserve capital. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. The Fund may take short positions on derivatives instruments.

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The portfolio managers’ investment process is research-driven, incorporating “top-down” and “bottom-up” factors to identify and manage exposure to risks across sectors, industries, and individual investments. The portfolio managers evaluate expected risk-adjusted returns on a portfolio and position level by analyzing fundamentals, valuations, and market technical indicators.

The Fund may lend portfolio securities on a short-term or long-term basis to certain qualified broker-dealers and institutions, 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 and yields will vary, and you could lose money. 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.

Fixed-Income Securities Risk. Fixed-income securities are generally subject to the following risks:

•

Interest rate risk is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise.

•

Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default.

•

Prepayment risk is the risk that, during periods of falling interest rates, certain debt obligations may be paid off quicker than originally anticipated, which may cause the Fund to reinvest its assets in securities with lower yields, resulting in a decline in the Fund’s income or return potential.

•

Extension risk is the risk that, during periods of rising interest rates, certain debt obligations may be paid off substantially slower than originally anticipated, and as a result, the value of those obligations may fall.

•

Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Valuation may also be affected by changes in the issuer’s financial strength, the market’s perception of such strength, or in the credit rating of the issuer or the security.

•

Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Consequently, the Fund may have to accept a lower price to sell a security, sell other securities to raise cash, or give up an investment opportunity, any of which could have a negative effect on the Fund’s performance. 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).

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds are considered speculative and may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Mortgage- and Asset-Backed Securities Risk. Mortgage- and asset-backed securities represent interests in “pools” of commercial or residential mortgages or other assets, including consumer loans or receivables. The value of mortgage- and asset-backed securities will be influenced by factors affecting the real estate market and the assets underlying these securities. Investments in mortgage-and asset-backed securities may be subject to credit risk, valuation risk, liquidity risk, extension risk, and prepayment risk. These securities also are subject to risk of default on the underlying mortgage or asset, particularly during periods of economic downturn.

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entities or private issuers because some or all of the mortgage default or credit risk associated with the underlying mortgage loans is transferred to investors. Additional risks associated with investments in CRTs may include valuation risk, mortgage credit risk, liquidity risk, and prepayment risk.

Foreign Exposure Risk. Foreign markets, including emerging 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 in emerging market countries, if any, may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Sovereign Debt Risk. Some investments in U.S. and non-U.S. government debt securities (“sovereign debt”) are considered low risk. However, investments in sovereign debt, especially the debt of certain emerging market countries, can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. In addition, to the extent the Fund invests in non-U.S. sovereign debt, it may be subject to currency risk.

Floating Rate Obligations Risk. The Fund may invest in floating rate obligations with interest rates that reset regularly, maintaining a fixed spread over a stated reference rate. The interest rates on floating rate obligations typically reset quarterly, although rates on some obligations may adjust at other intervals. Unexpected changes in the interest rates on floating rate obligations could result in lower income to the Fund. In addition, the secondary market on which floating rate obligations are traded may be less liquid than the market for investment grade securities or other types of income-producing securities, which may have an adverse impact on their market price. There is also a potential that there is no active market to trade floating rate obligations, that there may be restrictions on their transfer, or that the issuer may default. As a result, the Fund may be unable to sell floating rate obligations at the desired time or may be able to sell only at a price less than fair market value.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

TBA Commitments Risk. Although TBA securities must meet industry-accepted “good delivery” standards, there can be no assurance that a security purchased on a forward commitment basis will ultimately be issued or delivered by the counterparty. If the counterparty to a transaction fails to deliver the securities, the Fund could suffer a loss. Because TBA commitments do not require the delivery of a specific security, the characteristics of a security delivered to the Fund may be less favorable than expected. There is a risk that the security that the Fund buys will lose value between the purchase and settlement dates. TBA purchase and sales commitments may significantly increase the Fund’s portfolio turnover rate and are not included in the portfolio turnover rate calculation.

Derivatives Risk. Derivatives can be volatile and involve risks in addition to the risks of the underlying referenced securities or asset. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives entail the risk that the counterparty will default on its payment obligations. Derivatives used for hedging purposes may reduce or eliminate gains or cause losses if the market moves in a manner different from that anticipated by the portfolio managers or if the cost of the derivative outweighs the benefit of the hedge.

4 | Janus Investment Fund

incur a loss. This potential loss is theoretically unlimited. A short exposure through a derivative also exposes the Fund to credit risk, counterparty risk, and leverage risk.

Restricted Securities Risk. Securities that have limitations on their resale are referred to as “restricted securities.” Investments in restricted securities, including securities issued under Regulation S and Rule 144A, could have the effect of decreasing the Fund’s liquidity profile or preventing the Fund from disposing of them promptly at advantageous prices. Restricted securities 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.

LIBOR Replacement Risk. Certain debt securities, derivatives, or other financial instruments utilize the London InterBank Offered Rate (“LIBOR”) as a reference rate for various rate calculations. The U.K. Financial Conduct Authority stopped compelling or inducing banks to submit rates for many LIBOR settings and will continue to do so for certain other commonly-used U.S. dollar LIBOR settings after June 30, 2023. The elimination of LIBOR or other reference rates and the transition process away from LIBOR could adversely impact (i) volatility and liquidity in markets that are tied to those reference rates, (ii) the market for, or value of, specific securities or payments linked to those reference rates, (iii) the availability or terms of borrowing or refinancing, or (iv) the effectiveness of hedging strategies. For these and other reasons, the elimination of LIBOR or other reference rates may adversely affect the Fund’s performance and/or net asset value. Alternatives to LIBOR are established or in development in most major currencies including the Secured Overnight Financing Rate (“SOFR”) that is intended to replace the U.S. dollar LIBOR.

The effect of the discontinuation of LIBOR or other reference rates on the Fund will vary depending on, among other things (i) existing fallback or termination provisions in individual contracts and (ii) whether, how, and when industry participants develop and adopt new reference rates and fallbacks for both legacy and new products and instruments. Accordingly, it is difficult to predict the full impact of the transition away from LIBOR or other reference rates on the Fund until new reference rates and fallbacks for both legacy and new products, instruments, and contracts are commercially accepted.

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.

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

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, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012.

•

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, Class S Shares, and Class R 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.

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•

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.

If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, 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. 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.

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

Best Quarter:

2nd Quarter 2020

6.87%

Worst Quarter:

1st Quarter 2021

– 3.37%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2022 was – 15.03%.

Average Annual Total Returns (periods ended 12/31/21)
	1 Year	5 Years	10 Years	Since Inception (7/7/87)
Class T Shares
Return Before Taxes	– 0.96%	4.21%	3.58%	6.37%
Return After Taxes on Distributions	– 1.71%	3.10%	2.35%	4.17%
Return After Taxes on Distributions and Sale of Fund Shares(1)	– 0.56%	2.74%	2.23%	4.09%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)	– 1.54%	3.57%	2.90%	6.03%
Class A Shares
Return Before Taxes(2)	– 5.74%	2.98%	2.92%	6.17%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)	– 1.54%	3.57%	2.90%	6.03%

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Average Annual Total Returns (periods ended 12/31/21)
	1 Year	5 Years	10 Years	Since Inception (7/7/87)
Class C Shares
Return Before Taxes(3)	– 2.70%	3.35%	2.72%	5.64%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)	– 1.54%	3.57%	2.90%	6.03%
Class S Shares
Return Before Taxes	– 1.22%	3.91%	3.30%	6.18%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)	– 1.54%	3.57%	2.90%	6.03%
Class I Shares
Return Before Taxes	– 0.78%	4.36%	3.73%	6.43%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)	– 1.54%	3.57%	2.90%	6.03%
Class N Shares
Return Before Taxes	– 0.72%	4.44%	3.81%	6.44%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)	– 1.54%	3.57%	2.90%	6.03%
Class R Shares
Return Before Taxes	– 1.46%	3.66%	3.06%	5.93%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)	– 1.54%	3.57%	2.90%	6.03%

(1)

If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

(2)

Calculated assuming maximum permitted sales loads.

(3)

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

The Fund’s primary benchmark index is the Bloomberg U.S. Aggregate Bond Index. The index is described below.

•

The Bloomberg U.S. Aggregate Bond Index is made up of U.S. dollar-denominated, fixed-rate taxable bonds, including securities that are of investment grade quality or better.

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 Managers: Michael Keough is Executive Vice President and Co-Portfolio Manager of the Fund, which he has co-managed since December 2015. Greg Wilensky, CFA, is Executive Vice President and Co-Portfolio Manager of the Fund, which he has co-managed since February 2020.

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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.

8 | Janus Investment Fund

[JANUS HENDERSON LOGO]

Janus Henderson Flexible Bond Fund

Ticker:

JANFX

Class D Shares

Summary Prospectus dated October 28, 2022

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 Flexible Bond Fund seeks to obtain maximum total return, consistent with preservation 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		0.41%
Other Expenses		0.16%
Total Annual Fund Operating Expenses		0.57%

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	$ 58	$ 183	$ 318	$ 714

Principal investment strategies

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Principal investment risks

The biggest risk is that the Fund’s returns and yields will vary, and you could lose money. The principal risks associated with investing in the Fund are set forth below.

Fixed-Income Securities Risk. Fixed-income securities are generally subject to the following risks:

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Interest rate risk is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise.

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Credit Risk Transfer Securities Risk. CRTs are unguaranteed and unsecured debt securities that are commonly issued by a government sponsored entity. CRTs are not directly linked to or backed by the underlying mortgage loans, so investors such as the Fund have no direct recourse to the underlying mortgage loans in the event of a default. The risks associated with CRTs are different from the risks associated with investments in mortgage-backed securities issued by government sponsored entities or private issuers because some or all of the mortgage default or credit risk associated with the underlying mortgage loans is transferred to investors. Additional risks associated with investments in CRTs may include valuation risk, mortgage credit risk, liquidity risk, and prepayment risk.

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purchase and sales commitments may significantly increase the Fund’s portfolio turnover rate and are not included in the portfolio turnover rate calculation.

Short Exposure Risk. The Fund may enter into a derivatives transaction to obtain short investment exposure to the reference asset. If the value of the reference asset on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. This potential loss is theoretically unlimited. A short exposure through a derivative also exposes the Fund to credit risk, counterparty risk, and leverage risk.

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

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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. 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

6.90%

Worst Quarter:

1st Quarter 2021

– 3.35%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2022 was – 14.96%.

Average Annual Total Returns (periods ended 12/31/21)
	1 Year	5 Years	10 Years	Since Inception (7/7/87)
Class D Shares
Return Before Taxes	– 0.86%	4.29%	3.67%	6.41%
Return After Taxes on Distributions	– 1.65%	3.13%	2.41%	4.19%
Return After Taxes on Distributions and Sale of Fund Shares(1)	– 0.51%	2.78%	2.29%	4.11%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)	– 1.54%	3.57%	2.90%	6.03%

(1)

If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

The Fund’s primary benchmark index is the Bloomberg U.S. Aggregate Bond Index. The index is described below.

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The Bloomberg U.S. Aggregate Bond Index is made up of U.S. dollar-denominated, fixed-rate taxable bonds, including securities that are of investment grade quality or better.

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.

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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.

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.

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