U.S. stocks mostly up after weak start

For much of Wednesday, the U.S. stock market appeared to be headed for its third decline in three days.

By late afternoon, the market began to slowly pare its losses as investors bought up oil refiners, mining companies, and technology stocks.

The push was enough to nudge the Standard & Poor's 500 index into the green by a half-point. The tech-heavy Nasdaq composite also finished higher.

The S&P 500 index added 0.57 points, or 0.03 percent, to close at 1,868.20. The Dow Jones industrial average lost 11.17 points, or 0.07 percent, to 16,340.08.

The Nasdaq composite rebounded in the early afternoon, gaining 16.14 points, or 0.37 percent, to 4,323.33.

The three major U.S. stock indexes are still down for the week. Stocks had a strong finish last week, setting three record highs.

Investors have been worried this week about a sharp drop in China's exports in February reported over the weekend, which raised concerns that the world's second-largest economy was slowing. Since China is a big consumer of raw materials and energy, commodities such as copper and iron ore have dropped sharply. Copper has fallen to its lowest level since 2010, but recovered somewhat Wednesday.

A dearth of major U.S. economic news helped dampen trading Wednesday.

While China growth concerns appeared to hurt oil prices Wednesday, it didn't stop investors from buying up oil refiners.

Tesoro Corp. rose the most of any stock in the S&P 500 index, climbing $2.13, or 4.1 percent, to $54.50. Marathon Petroleum Corp. added $3.21, or 3.5 percent, to $94.50, while Valero Energy Corp. gained $1.62, or 3 percent, to $55.29.

Investors also took a shine to mining companies as metals prices increased. Cliffs Natural Resources Inc. rose 43 cents, or 2.4 percent, to $18.41 and Newmont Mining Corp. rose 66 cents, or 2.7 percent, to $25.01.

Google, Microsoft and Facebook also contributed to the day's gains. Google rose $7.31, or 0.6 percent, to $1,207.30; Microsoft added 25 cents, or 0.7 percent, to $38.27; and Facebook climbed 78 cents, or 1.1 percent, to $70.88.