What is 'Asset Size'

Asset size is the total market value of the securities in a fund. It can also be referred to as assets under management. Funds regularly report total assets which can be affected by supply, demand and market return.


Asset size for mutual funds is often reported by share class. When it comes to the size of a mutual fund for investment, bigger is not necessarily better. Key aspects for investment fund quality and investment consideration are typically the fund’s investment style and its ability to meet or exceed the returns of market benchmarks through its investment allocations.

However, the asset size of a fund can be important for investors to consider for a few reasons. While asset size does not greatly influence a fund’s performance, top investment managers and top performing funds are likely to see greater fund inflows. Investors in funds with a larger asset size can also benefit from greater economies of scale which translate to lower fund expense ratios since the expense ratio is calculated as a percent of total assets. Larger funds also tend to be more actively traded in the market with higher average daily trading volume providing for greater market liquidity.

Asset Size Volatility

Asset size can be affected by supply, demand and market return. Increasing market return is a positive factor that increases the value of the portfolio from market gains. Capital appreciation is a top priority for investment managers and a metric that is easily followed by investors. However, when assets rapidly increase from inflows so-called "asset bloat" may occur which can present challenges for the portfolio managers. Capital inflows and outflows can substantially affect operational and transaction costs. Many funds have redemption fees for short-term redemptions which help support trading activities when investors redeem.

Substantial inflows to a fund are what cause asset bloat. This is pre-dominantly an issue with active funds. Active investment managers must deploy funds into current allocations or they may choose to invest in new securities. Some funds may also limit the asset size capacity of their funds. Investment managers can choose to close funds to new investors for various reasons with asset capacity often a factor in fund closings.

Largest U.S. Funds by Asset Size

MarketWatch provides details on the investment market’s largest funds by asset size. Funds are reported by share class assets. As of January 9, 2018, Vanguard dominated the top ten list with seven of the largest funds in the investment market.

Rank Fund Name Symbol

1 SPDR S&P 500 ETF (SPY)

2 Vanguard 500 Index Fund Admiral Shares (VFIAX)

3 Vanguard TSM Index Fund Admiral Shares (VTSAX)

4 iShares Core S&P 500 (IVV)

5 Vanguard Institutional Index Fund Institutional Shares (VINIX)

6 Fidelity Government Cash Reserves (FDRXX)

7 Vanguard TSM Index Investor Shares (VTSMX)

8 Vanguard TSM Index Institutional Plus Shares (VSMPX)

9 Vanguard Total Stock Investor Shares (VGTSX)

10 Vanguard TSM Index Institutional Shares (VITSX)

  1. Minimum Investment

    A minimum investment is the smallest dollar or share quantity ...
  2. Total Stock Fund

    A total stock fund is a mutual fund or exchange-traded fund that ...
  3. Investment Fund

    An investment fund is the pooled capital of investors that enables ...
  4. Asset Allocation Fund

    An asset allocation fund is a fund that provides investors with ...
  5. Mutual Fund

    Mutual funds combine money from many investors to invest in a ...
  6. Active Index Fund

    Active index funds track an index fund with an additional layer ...
Related Articles
  1. Investing

    Top 5 Biggest Mutual Funds of 2017

    Vanguard takes top billing again in 2017 when it comes to supersized mutual funds. Here's our list of the rest of the top 5 largest.
  2. Investing

    American Funds Vs. The Vanguard Group

    Here are the differences between two of the largest mutual fund families, American Funds and Vanguard Funds, and how the two companies' returns match up.
  3. Financial Advisor

    4 Top U.S. Equity Index Mutual Funds

    These four funds are among the best U.S. equities index mutual funds for core holdings in your investment portfolio.
  4. Retirement

    3 Vanguard Target-Date Retirement Funds

    Vanguard offers mutual funds for target retirement dates for every five years from 2020 to 2065. They're ideal for investments of at least 10 years.
  5. Investing

    Vanguard Balanced Allocation Funds Overview

    Learn about the basics of Vanguard Funds and how their Balanced allocation mutual funds and ETFs differ from other investment managers.
  6. Investing

    These Top Vanguard Funds Will Help You Diversify

    These Vanguard funds offer diversification and low fees for retirement savers.
  7. Retirement

    The 8 Most Popular Vanguard Funds for a 401(k)

    Learn about some of the mutual funds in Vanguard's lineup that are popular among 401(k) investors, and find out why you should consider them.
  8. Investing

    Vanguard Equity Index Funds Overview (VFINX, VTSAX)

    Learn about Vanguard's investment philosophy and its equity index mutual fund offerings, which encompass substantially all equity fund sectors.
  9. Investing

    The 3 Best Performing Vanguard Funds of 2015

    Learn about three Vanguard mutual funds that had the highest returns in 2015 and invest in the health care sector, broad market and international stocks.
  10. Personal Finance

    North Carolina 529 College Savings Plan: Investment Plan Analysis

    Learn about the 529 North Carolina College Savings Plan, complete with a summary of the plan and different investment options that are provided by Vanguard.
  1. Mutual funds versus money market funds

    Learn what mutual funds and money market funds are and understand the differences between each, as well as how they serve ... Read Answer >>
Trading Center