* Oil pares gains after data shows U.S. crude buildup
* Amazon biggest drag on S&P 500, Nasdaq
* Five S&P sectors down more than 1 pct
* Indexes down: Dow 0.77 pct, S&P 0.81 pct, Nasdaq 1.26 pct (Updates to early afternoon)
By Abhiram Nandakumar
Jan 13 (Reuters) - Wall Street moved lower on Wednesday, as an early rally once again faded, with Amazon leading consumer discretionary stocks lower and crude oil prices struggling to end a seven-day losing streak.
Nine of the 10 major S&P sectors were lower. While consumer stocks were down through the day, other sectors, including energy and industrial stocks, turned negative around midday.
Crude prices once again slid towards $30 per barrel, but held ground above the key level, as U.S. crude stockpiles rose more than expected last week.
Amazon fell 3.6 percent to a 2-1/2 month low of $598.50 and was the biggest drag on the S&P 500 and the Nasdaq.
Stocks as well as oil prices rose earlier in the session after positive Chinese trade data allayed concerns about the health of the world's second-biggest economy.
"It's becoming quite apparent that any strength is being used to trim or exit positions as opposed to taking on new positions in the market, at least in the last couple of days," said Ryan Larson, head of U.S. equity trading at RBC Global Asset Management in Chicago.
U.S. stocks have been following a pattern over the last few sessions: an early rally that fizzles out by the afternoon, followed by a surge near the end of the day.
At 12:40 p.m. ET (1740 GMT), the Dow Jones industrial average was down 127.34 points, or 0.77 percent, at 16,388.88.
The S&P 500 was down 15.73 points, or 0.81 percent, at 1,922.95 and the Nasdaq Composite index was down 58.99 points, or 1.26 percent, at 4,626.93.
The consumer discretionary sector was down 1.43 percent. Four other sectors, including energy, were down more than 1 percent.
Financial stocks were down 1.2 percent. JPMorgan , which kicks off the earnings season for the sector on Thursday, was down 1.4 percent at $58.12.
Express Scripts was down 5.7 percent at $80.69 after health insurer Anthem said it was renegotiating a contract with the pharmacy benefits manager.
CSX was down 6.8 percent at $22.10 after the railroad company's fourth-quarter profit fell on declining freight volumes.
Other railroad stocks were also down: Norfolk Southern slid 6 percent and Union Pacific was down 2.9 percent.
Among the bright spots were Microsoft shares, up 0.7 percent to $53.14 on a Morgan Stanley rating upgrade.
Metlife was up 4.6 percent at $43.94 after the biggest U.S. life insurer said it plans to separate a large part of its retail business.
The U.S. Treasury Department is scheduled to release its budget report for December at 2 p.m.
Declining issues outnumbered advancing ones on the NYSE by 2,161 to 820. On the Nasdaq, 2,026 issues fell and 689 advanced.
The S&P 500 index showed two new 52-week highs and 37 new lows, while the Nasdaq recorded six new highs and 257 new lows. (Reporting by Abhiram Nandakumar in Bengaluru; Editing by Savio D'Souza)