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 ...