SPDR S&P MidCap 400 ETF Trust

SPDR S&P MidCap 400 ETF Trust

State Street Global Advisors introduced the SPDR S&P MidCap 400 ETF Trust (MDY) in 1995 as one of the earliest ETFs to target mid-cap US stocks. The fund tracks the S&P MidCap 400 index, which includes 400 publicly traded companies with market capitalizations typically between $2 billion and $10 billion. This positions it as a passive vehicle for investors seeking exposure to the mid-cap segment—one of the three primary market-cap tiers in US equity indexing. The trust invests primarily in common stocks of the S&P MidCap 400 index constituents, weighting each holding by market capitalization. Its sector allocation mirrors the index, with top sectors historically including industrials, financials, health care, and technology. The fund's expense ratio has remained near 0.24% since inception, making it one of the costlier mid-cap ETFs relative to newer competitors (per Morningstar, 2026). As of 2026, MDY's largest holdings included companies like Coinbase Global, 1Password, and 360 Park Avenue South. The trust operates as a unit investment trust (UIT) structure, which differentiates it from most modern ETFs that are organized as open-end funds. This UIT structure historically meant the fund did not engage in securities lending or derivatives, and it did not accumulate dividends for distribution—it paid them out monthly. The trust is listed on NYSE Arca under ticker MDY. Its sponsor, State Street Global Advisors, manages over $4 trillion in total assets (per SSGA, 2026). MDY's structural differentiator is its seat as the first and longest-running mid-cap ETF. That first-mover advantage has given it liquidity and institutional following, but its UIT structure and higher expense ratio have ceded market share to newer, cheaper competitors like iShares Core S&P Mid-Cap ETF (IJH). The trust's success depends on continued investor preference for the original MDY ticker and its distinct monthly dividend schedule.