*Sony surges as U.S. fund calls on to spin off unit Exporters lead the gains on further weakening of yen. TOKYO, May 15- Japan's Nikkei share index rose 2.2 percent to break above 15,000 on Wednesday, with Sony Corp surging after a proposal from a U.S. activist fund to list its entertainment unit sent its U.S.-listed shares soaring 10 percent.
*Sony option and share volume far above normal on Monday. *Sony option volume hits records Monday, Tuesday- Trade Alert.
*Sony option and share volume far above normal on Monday. May 14- A surge in option market bets on Sony Corp just before a large hedge fund investor announced a big stake and called for a major restructuring of the company has raised concerns that some traders may have had advance word of the news.