Vanguard is the best-selling U.S. family of exchange traded funds so far this year and continues to gain ground on State Street Global Advisors, the second-largest ETF provider.

Total assets in State Street’s U.S.-listed ETFs totals $311.5 billion, while Vanguard weighs in at $297.8 billion, according to XTF.com.

It’s important to note the State Street figure does not include SPDR Gold Shares (NYSEArca: GLD), which holds nearly $38 billion of assets. GLD is technically sponsored by a unit of the World Gold Council, while State Street is the ETF’s marketing agent.

Through the end of July, Vanguard had pulled in net ETF flows of $33.9 billion year to date in the U.S., according to data from BlackRock, which manages the iShares ETFs.

State Street’s YTD inflows at its U.S.-listed ETFs totaled $7.5 billion — but that figure does include GLD. State Street’s inflows would be much higher if GLD is stripped out. The gold ETF saw net outflows of nearly $20 billion so far this year through the end of July. [GLD Battles to Keep Spot Among Largest ETFs]

State Street’s SPDR S&P 500 (NYSEArca: SPY) is the largest ETF in the world with about $155.5 billion. It has hauled in about $8.6 billion so far in 2013 as of July 31, according to IndexUniverse data.

BlackRock’s iShares is the largest U.S. ETF provider with assets of $607.5 billion, according to XTF. Through July, it saw net inflows of $20.6 billion so far in 2013.

Overall, the U.S. exchange traded product business stood at roughly $1.5 trillion at the end of July, with year-to-date inflows of $115 billion.

Full disclosure: Tom Lydon’s clients own GLD and SPY.