SPDR S&P 500 ETF Trust (SPY)

What is SPY?

SPY was one of the first exchange-traded funds launched in the United States and tracks the S&P 500 index. Unlike more recently launched S&P 500 ETFs, SPY is organized as a unit investment trust (UIT) rather than an open-end fund, an older legal structure that comes with some operational differences, such as how dividends are handled before distribution.

How SPY compares

SPY tracks the same S&P 500 index as VOO and IVV. Its most distinctive feature is trading volume: SPY's average daily share volume is dramatically higher than VOO's or IVV's, making it a common choice for short-term trading, options markets and institutional activity, alongside long-term investors who also hold it.

Risks and considerations

SPY's performance reflects the S&P 500 index and is subject to the same broad market risk as any large-cap US equity fund. Its UIT structure also means it cannot reinvest dividends immediately the way some open-end funds can, holding cash between distributions instead.

Long-term investing considerations

High trading volume is primarily relevant to traders seeking tight bid-ask spreads; it does not change the fund's underlying long-term exposure to the S&P 500. Long-term investors comparing SPY with similar funds often weigh cost and structure alongside liquidity.