S&P 500 top movers: Energy stocks surge higher on crude oil rally

• S&P 500 Index registers modest daily gains on Wednesday.
• Rising crude oil prices provide a boost to energy stocks.
• Illumina Inc (ILMN: NASDAQ) shares are down more than 7%.

The S&P 500 Index (SPX) started the day modestly higher and stayed relatively quiet during the first half of the session on Wednesday as investors wait for the Federal Reserve's policy announcements. As of writing, the SPX was up 0.2% on a daily basis at 3,407.

S&P 500 top movers

Surging crude oil prices help energy stocks pots strong gains. At the moment, the barrel of West Texas Intermediate (WTI) is up more than 4% on a daily basis, trading near $40. Among the top energy stocks, Diamondback Energy Inc (FANG: NASDAQ), Occidental Petroleum Corp (OXY: NYSE), ONEOK Inc (OKE: NYSE), Marathon Oil Corp (MRO: NYSE), Cimarex Energy Co (XEC: NYSE) and Devon Energy Corp (DVN: NYSE) shares are up between 9% and 5.8%.

On the other hand, Illumina Inc (ILMN: NASDAQ)  shares fell sharply on Wednesday following a report from Bloomberg claiming that the company was in talks to buy cancer testing startup Grail. At the moment, ILMN is down 7.1% on the day at $327.65 as the biggest percentage decliner of the day.