Amid dynamic changes in the exchange-traded fund (ETF) market, competition among the leading players is intensifying. The Vanguard Group Standard & Poor's 500 $VOO is rapidly closing the gap with the iconic SPDR S&P 500 Trust $SPY , offered by State Street Global Advisors. According to data from FactSet, LSEG, and other sources, the asset gap has been steadily narrowing in recent months, even though, as of the close on Friday, State Street still led with $633.1 billion in assets compared to Vanguard ETF’s $631.8 billion.