On Thursday, Google (NasdaqGM: GOOG) closed with a market value of nearly $403 billion, usurping Exxon Mobil (NYSE: XOM) as the second-largest U.S. company behind Apple (Nasdaq: AAPL).

Given Exxon’s disappointing performance this year, shares of the largest U.S. oil company, are down almost 8%, investors in S&P 500 index funds might be pleased to see Exxon take a small step back in terms of weight in the benchmark U.S. index.

Investors in energy ETFs dominated by Exxon could use some relief as well.

“Given Exxon Mobil’s heavy weighting in these funds, the company’s performance can have a large effect on the performance of these ETFs,” writes Ingrid Pan for Market Realist.

While that may stating the obvious, Exxon’s impact on ETFs such as the Energy Select Sector SPDR (NYSEArca: XLE) and the Vanguard Energy ETF (NYSEArca: VDE) cannot be overlooked. [Energy ETFs Look to Bounce Back]

XLE allocates almost 16% of its weight to Exxon. At the end of January, VDE’s Exxon allocation was 23% and those are not the only ETF with substantial weights to Exxon. The new Fidelity MSCI Energy Index ETF (NYSEArca: FENY) does not skimp on Exxon with almost 22% weight to the oil giant while the iShares U.S. Energy ETF (NYSEArca: IYE) devotes 22.2% to the stock.