Looking at their performances, SPY has gained 18.8% year-to-date, VOO increased 18.9% and IVV rose 18.8%. The S&P 500 Index has provided a 18.9% return so far this year.

Previously, the SPDR Gold Trust (NYSEArca: GLD) briefly surpassed SPY as the largest ETF when gold prices were trading at a record high in 2011. GLD is now the fifth largest U.S.-listed ETFs, with $39 billion in assets. The gold fund has suffered from a steep decline in gold prices and heavy redemptions. [Largest Bullion ETF’s Assets Cut in Half on Gold Plunge, Outflows]

For more information on the S&P 500, visit our S&P 500 category.

Max Chen contributed to this article.