SAN FRANCISCO (AP) — A major Yahoo shareholder who exposed a fabrication on the new CEO's academic credentials is demanding that the Internet company fire him for unethical conduct.In a letter Friday, activist hedge fund manager Daniel Loeb urged Yahoo's board to dump CEO Scott Thompson. Loeb indicated he would consider filing a lawsuit if the board doesn't take "swift and decisive" action by noon ET Monday.Thompson's job appears to be in jeopardy because Thompson's bio included a computer science degree that he never received. Loeb revealed the distortion Thursday. The error was in a recent regulatory filing and Yahoo's website.Yahoo Inc. initially brushed off the misrepresentations as an "inadvertent error." Late Thursday, the company said its board would investigate what happened.Yahoo didn't immediately return a message for comment.