Expense ratio

An expense ratio is the annual fee a fund charges its investors, expressed as a percentage of assets under management, to cover management fees, administration, and other operating costs. It is deducted continuously from the fund's assets rather than billed separately, so it reduces the fund's reported return directly rather than appearing as a line-item charge.

It is calculated as total annual fund operating expenses / average fund assets, and is usually quoted alongside a fund's other figures, such as its tracking error against a benchmark index for index funds. Actively managed funds generally carry higher expense ratios than passive index funds and exchange-traded funds, reflecting the cost of research and active decision-making, though a higher fee does not by itself imply better performance.

Investors compare expense ratios because, unlike future returns, costs are known in advance and compound over long holding periods: a seemingly small difference, such as 0.50% versus 1.50% a year, can amount to a substantial share of total returns over decades. A common pitfall is comparing expense ratios alone without accounting for what else is bundled into the fee, such as advice, or ignoring other costs like trading spreads and sales loads that are not captured in the expense ratio itself.