* U.S. stocks briefly turn negative
* Crude oil slips on report of higher stockpiles
* Tech stocks weigh, Apple biggest drag on market
* Yum Brands hit by China woes, drags McDonald's
* Indexes up: Dow 0.15 pct, S&P 0.20 pct, Nasdaq 0.07 pct (Updates to early afternoon)
By Tanya Agrawal
Oct 7 (Reuters) - U.S. stocks were marginally higher in volatile trading on Wednesday as investor worries about corporate earnings grew and a rally in crude oil prices ended.
Crude oil prices seesawed after government data showing a large U.S. crude inventory build surprised traders the morning after an industry group had reported a draw.
The S&P energy index, earlier the best performing among the 10 major S&P sectors, was up 0.13 percent - the smallest gain among the six advancing S&P sectors.
U.S. stocks opened up strongly, turned negative for a while as oil prices slipped before eking out a small gain in afternoon trading.
"There is no real conviction in either direction in the market," said Joseph Benanti, managing director, sales and trading of Rosenblatt Securities in New York.
At 12:48 p.m. ET (1648 GMT) the Dow Jones industrial average was up 24.89 points, or 0.15 percent, at 16,815.08. The S&P 500 was up 4.04 points, or 0.2 percent, at 1,983.96 and the Nasdaq composite index was up 3.35 points, or 0.07 percent, at 4,751.71.
Benanti said investors are going to be looking pretty closely at Alcoa's report after the bell on Thursday and its effect on the metals market, and any revisions in guidance by companies.
Investors have become increasingly concerned about slowing global growth, especially in China, and its effect on corporate results.
S&P 500 companies are expected to report a 4.2 percent fall in third-quarter profit, the biggest decline in six years, according to Thomson Reuters data.
"Tech investors are very worried heading into earnings season and this has been an overhang with many of the tech stalwarts having a bullseye on their back," said Daniel Ives, senior analyst at FBR Capital.
"Worries about earnings into the back half is a major issue for the Street."
The S&P telecommunications index's 0.83 percent drop was the biggest decline, while the technology index followed with a 0.59 percent drop. Apple was down 1.4 percent and was the biggest drag on all three indexes.
The health care index's 1.2 percent gain was the best among S&P sectors. A sell off in healthcare and biotech stocks had weighed on the market on Tuesday.
Yum Brands slumped 18.1 percent to $68.32 after its results showed a slower-than-expected recovery in China. McDonald's, which also has a large exposure to China, fell about 1 percent to $101.12.
Adobe fell 7 percent to $79.23 after lowering its 2016 profit forecast.
Twitter rose 5 percent to $28.99 after Saudi Arabian billionaire Prince Alwaleed bin Talal and his investment firm raised their stake to more than 5 percent.
Advancing issues outnumbered decliners on the NYSE by 2,080 to 879. On the Nasdaq, 1,884 issues rose and 835 fell.
The S&P 500 index showed eight new 52-week highs and no new lows, while the Nasdaq recorded 32 new highs and 26 new lows. (Reporting by Tanya Agrawal and Abhiram Nandakumar; Additional reporting by Devika Krishna Kumar; Editing by Savio D'Souza)