The Dow Jones Industrial Average gained 38.59 points to 12,252.39.
The S&P 500 rose 3 points to 1,326.75 and the Nasdaq Composite added 8 points to 2,260.28, with 25 of its 30 components posting early gains.
Early trade had technology stocks largely on the rise, with bellwether Cisco Systems Inc. edging up after its chairman and CEO expressed increased comfort with the networking titan's longer-term growth prospects.
And, Yahoo Inc. gained 0.3% after the Internet search engine extended its deadline for nominating directors to its board.
On the New York Mercantile Exchange, crude-oil futures rose $1.80 to $101.32 a barrel, while gold advanced $10.70 to $977.00 an ounce.
Reports a bailout of Ambac Financial Inc. was back on the table fueled a late-day rally Tuesday, pulling U.S. stock indexes off earlier lows.
The private sector shed 23,000 jobs in February, according to the ADP employment report released early Wednesday.
Adding in some 25,000 jobs typically created by government, the ADP report suggests nonfarm payrolls grew by about 2,000, compared to the 20,000 forecast by economists. .
Also out, data showing the productivity of U.S. nonfarm businesses and unit labor costs -- a key inflation gauge -- were revised slightly higher in the fourth quarter than prior estimates. .
At 10 a.m. Eastern, data on January factory orders will be released.
Oil futures were back above $100 a barrel, up 93 cents to $100.46 a barrel, as OPEC left production unchanged.
Costco Wholesale Corp. was down nearly 3% after its report of a 31% profit rise met expectations, while Big Lots Inc. gained 16.5% after reporting a 12% profit fall.
Overseas markets were split, with Asian stocks generally posting a flat performance, while stocks in Europe rose after five straight losses.
The Nikkei 225 ended 0.2% lower in Tokyo, while the German DAX 30 rose 1.2%.
By Kate Gibson