A sticking point in talks between Columbia/HCA Corp. and Tenet Healthcare Corp. over a potential combination centers on how to value Columbia because it may have to pay a major fine to settle possible fraud charges, according to people familiar with the situation. Tenet and Columbia are discussing a structure that would have Tenet purchase much-bigger Columbia, say people familiar with the situation. While Tenet shareholders might end up owning a minority of the combined company, Tenet managers would lead the new entity, the people say. Tenet could be the surviving name under this scenario. Wall Street appeared to like the idea of a possible combination, which was reported yesterday in The Wall Street Journal. In composite trading on the New York Stock Exchange, Columbia shares rose $3.25, or 9.8%, to close at $36.3125. Tenet shares climbed $2.625, or 9.5%, to $30.125.