Summary Prospectus by Investment Company - Form 497K

Vanguard Variable Insurance Funds

Conservative Allocation Portfolio

Summary Prospectus

April 26, 2024

The Portfolio's statutory Prospectus and Statement of Additional Information dated April 26, 2024, as may be amended or supplemented, are incorporated into and made part of this Summary Prospectus by reference.

Before you invest, you may want to review the Portfolio's Prospectus, which contains more information about the Portfolio and its risks. You can find the Portfolio's Prospectus and other information about the Portfolio online at www.vanguard.com/prospectus. You can also obtain this information at no cost by calling 800-522-5555 or by sending an email request to [email protected].

The Securities and Exchange Commission (SEC) has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Investment Objective

The Portfolio seeks to provide current income and low to moderate capital appreciation.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy, hold, and sell shares of the Portfolio. The expenses shown in the table and in the example that follows do not reflect additional fees and expenses associated with the annuity or life insurance program through which you invest. If those additional fees and expenses were included, overall expenses would be higher.

Annual Portfolio Operating Expenses
(Expenses that you pay each year as a percentage of the value of your investment)

Management Fees	0.00 %
12b-1 Distribution Fee	None
Other Expenses	0.00 %
Acquired Fund Fees and Expenses	0.13 %
Total Annual Portfolio Operating Expenses	0.13 %

Example

The following example is intended to help you compare the cost of investing in the Portfolio (based on the fees and expenses of the acquired funds) with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you were to invest $10,000 in the Portfolio's shares. This example assumes that the Portfolio provides a return of 5% each year and that total annual operating expenses (of the Portfolio and its underlying funds) remain as stated in the preceding table. You would incur these hypothetical expenses whether or not you were to redeem your investment at the end of the given period. 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
$13	$42	$73	$166

Portfolio Turnover

The Portfolio may pay transaction costs, such as purchase fees, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in

annual portfolio operating expenses or in the previous expense example, reduce the Portfolio's performance. During the most recent fiscal year, the Portfolio's turnover rate was 13% of the average value of its portfolio.

Principal Investment Strategies

Vanguard Variable Insurance Funds Conservative Allocation Portfolio (the Conservative Allocation Portfolio) invests in a mix of Vanguard mutual funds and other portfolios of Vanguard Variable Insurance Funds (collectively, the underlying funds) according to an asset-allocation strategy that reflects an allocation of approximately 60% of the Portfolio's assets to fixed income securities and 40% to common stocks. The targeted percentage of the Portfolio's assets allocated to the underlying asset classes is:

• U.S. fixed income securities - 42%
• Large-cap U.S. stocks - 20%
• Foreign fixed income securities - 18%
• Foreign stocks - 16%
• Small- and mid-cap U.S. stocks - 4%

The Portfolio's indirect fixed income holdings are a diversified mix of short-, intermediate-, and long-term U.S. government, U.S. agency, and investment-grade U.S. corporate bonds; mortgage-backed and asset-backed securities; and government, agency, corporate, and investment-grade foreign bonds issued in currencies other than the U.S. dollar (but hedged by Vanguard, typically with foreign currency exchange forward contracts, to minimize foreign currency exposure). The Portfolio's indirect stock holdings are a diversified mix of U.S. and foreign large-, mid-, and small-capitalization stocks.

The Portfolio uses its investment in large-cap U.S. stocks and small- and mid-cap U.S. stocks to gain exposure to the overall domestic stock market. Although the percentage of the Portfolio's assets invested in either of these two asset classes may deviate slightly from the target allocation, the combination of the two asset classes will equal approximately 24% of the Portfolio's assets in the aggregate.

The board of trustees of Vanguard Variable Insurance Funds may change the targeted allocation to the underlying asset classes without shareholder approval.

Principal Risks

The Portfolio is subject to the risks associated with the stock and bond markets, any of which could cause an investor to lose money, and the level of risk may vary based on market conditions. However, because fixed income securities

such as bonds usually are less volatile than stocks and because the Portfolio invests more than half of its assets in fixed income securities, the Portfolio's overall level of risk should be low to moderate.

• With a target allocation of approximately 60% of its assets to fixed income securities, the Portfolio is proportionately subject to bond risks, including the following: interest rate risk, which is the chance that bond prices overall will decline because of rising interest rates; credit risk, which is the chance that the issuer of a security will fail to pay interest or principal in a timely manner, or that negative perceptions of the issuer's ability to make such payments will cause the price of that security to decline, thus reducing an underlying fund's return; and income risk, which is the chance that an underlying fund's income will decline because of falling interest rates. If an underlying fund holds securities that are callable, the underlying fund's income may decline because of call risk, which is the chance that during periods of falling interest rates, issuers of callable bonds may call (redeem) securities with higher coupon rates or interest rates before their maturity dates. An underlying fund would then lose any price appreciation above the bond's call price and would be forced to reinvest the unanticipated proceeds at lower interest rates, resulting in a decline in the underlying fund's income. For mortgage-backed securities, this risk is known as prepayment risk. The Portfolio is also subject to the following risks associated with investments in currency-hedged foreign bonds: country/regional risk, which is the chance that world events-such as political upheaval, financial troubles, or natural disasters-will adversely affect the value and/or liquidity of securities issued by foreign governments, government agencies, or companies; and currency hedging risk, which is the chance that the currency hedging transactions entered into by the underlying international bond fund may not perfectly offset the fund's foreign currency exposure.

• With approximately 40% of its assets allocated to stocks, the Portfolio is proportionately subject to stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. The Portfolio is also subject to the following risks associated with investments in foreign stocks: country/regional risk, which is the chance that world events-such as political upheaval, financial troubles, or natural disasters-will adversely affect the value of securities issued by companies in foreign countries or regions; and currency risk, which is the chance that the value of a foreign investment, measured in U.S. dollars, will decrease because of unfavorable changes in currency exchange rates. Country/regional risk and currency risk are especially high in emerging markets.

• Asset allocation risk, which is the chance that the selection of underlying funds, and the allocation of assets to them, will cause the Portfolio to underperform other funds with a similar investment objective.

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

Annual Total Returns

The following bar chart and table are intended to help you understand the risks of investing in the Portfolio. The bar chart shows how the performance of the Portfolio has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Portfolio compare with those of relevant market indexes and a composite bond/stock index, which have investment characteristics similar to those of the Portfolio. The Conservative Allocation Composite Index is weighted 42% Bloomberg U.S. Aggregate Float Adjusted Index, 24% S&P Total Market Index, 18% Bloomberg Global Aggregate ex-USD Float Adjusted RIC Capped Index (USD Hedged), and 16% FTSE Global All Cap ex US Index as of April 28, 2017. Previously, the composite was weighted 48% Bloomberg U.S. Aggregate Float Adjusted Index, 28% S&P Total Market Index, 12% Bloomberg Global Aggregate ex-USD Float Adjusted RIC Capped Index (USD Hedged), and 12% FTSE Global All Cap ex US Index from June 3, 2013, through April 27, 2017. International stock benchmark returns are adjusted for withholding taxes. The Portfolio's returns are net of its expenses, but do not reflect additional fees and expenses that are deducted by the annuity or life insurance program through which you invest. If such fees and expenses were included in the calculation of the Portfolio's returns, the returns would be lower. Keep in mind that the Portfolio's past performance does not indicate how the Portfolio will perform in the future. Updated performance information is available on our website for Financial Advisors at advisors.vanguard.com or by calling Vanguard toll-free at 800-522-5555.

Annual Total Returns - Conservative Allocation Portfolio

During the periods shown in the bar chart, the highest and lowest returns for a calendar quarter were:

	Total Return	Quarter
Highest	9.74 %	June 30, 2020
Lowest	-9.15 %	June 30, 2022

Average Annual Total Returns for Periods Ended December 31, 2023

	1 Year	5 Years	10 Years
Conservative Allocation Portfolio	12.51 %	5.60 %	4.84 %
Conservative Allocation Composite Index (reflects no deduction for fees, expenses, or taxes)	12.71 %	5.90 %	5.07 %
Bloomberg U.S. Aggregate Float Adjusted Index (reflects no deduction for fees, expenses, or taxes)	5.60	1.17	1.83
Dow Jones U.S. Total Stock Market Float Adjusted Index (reflects no deduction for fees, expenses, or taxes)	26.06	15.05	11.40

Investment Advisor

The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Roger A. Aliaga Diaz, Ph.D., Portfolio Manager, Investment Strategy Group, at Vanguard. He has co-managed the Portfolio since 2023.

Aurélie Denis, CFA, Portfolio Manager at Vanguard. She has co-managed the Portfolio since 2023.

Michael R. Roach, Portfolio Manager at Vanguard. He has co-managed the Portfolio since 2023.

Walter Nejman, Portfolio Manager at Vanguard. He has co-managed the Portfolio since 2013.