2.3.9 Assets Under Management (AUM)

What the figure represents

AUM is simply the sum of every investor's money currently held in a fund, or across an entire AMC's schemes. It is often used as a rough proxy for popularity and trust, since money tends to flow toward funds with a track record investors are comfortable with.

AUM (Assets Under Management) is the total market value of all investments held by a mutual fund scheme or across all schemes of an AMC. It fluctuates daily with market movements and investor flows (new purchases and redemptions). A fund with ₹50,000 crore in AUM is managing a larger pool than one with ₹5,000 crore, which has implications for liquidity, market impact and operational efficiency.

Where size becomes a genuine constraint

A small cap fund with a large AUM faces a real practical problem that a large cap fund of the same size generally does not: there simply may not be enough shares in smaller companies for the fund to build a meaningful position without materially moving that stock's price. This is one reason some small cap and mid cap funds have periodically closed to new investors once they reached a certain size.

Larger AUM generally benefits debt funds and large-cap equity funds. In debt, a larger fund can negotiate better pricing on bond purchases and has more flexibility in portfolio construction. In large-cap equity, size rarely constrains the manager because the underlying stocks are highly liquid. However, in mid-cap and small-cap equity, large AUM can become a handicap. A small-cap fund managing ₹30,000 crore needs to deploy money across a universe of stocks with limited liquidity. Large buy orders can push prices up (increasing the purchase cost), and large sell orders can push prices down (reducing the exit price). This market impact erodes returns in a way that does not affect smaller funds.

SEBI introduced AUM-based expense ratio slabs to ensure that the economies of scale from larger AUM are passed through to investors in the form of lower fees. As a fund's AUM grows, its permitted expense ratio declines on a slab basis. This means the largest funds tend to have the lowest expense ratios within their category, which is one genuine advantage of scale for the investor.

How to think about AUM sensibly

AUM size is far more relevant for small and mid cap funds than for large cap or index funds, where liquidity is rarely a binding constraint given how heavily traded large companies typically are. AUM alone says nothing about quality; it is one input to weigh, particularly for funds investing in less liquid corners of the market, rather than a standalone signal of a good or bad fund.