Sotheby's sold a Mark Rothko abstract for $75 million on Tuesday in a contemporary-art auction whose total—$375 million—surpassed any in its company history. Fittingly, the Rothko painting is titled, "No. 1 (Royal Red & Blue)."

The sale of the 1954 Rothko—with its floating red, pink and blue rectangles—pushed the auction house's sale total over the $362 million it got from a similar evening sale in May 2008 that marked the peak of the last market cycle. It's unclear whether Tuesday's performance amounts to a similar cresting, but in the short term it could boost collectors' confidence in art values—especially after last week's disappointing sales of Impressionist and modern art.

The sellers of the Rothko, John Marion, a former Sotheby's president, and his oil-heiress wife, Anne, only expected their painting to sell for up to $50 million. But at least five bidders chased after the abstract, and bids came quickly for a few minutes before the competition slowed to a pair of dogged telephone bidders. The winning bid was ultimately fielded by Charlie Moffett, a Sotheby's specialist who typically works with American collectors....