Toshiba's stock has been sliced in half since late December when it first flagged multi-billion-dollar losses at U.S. nuclear unit Westinghouse Electric, and revealed allegations of accounting fraud by senior managers at the division. Yesterday, Toshiba said it was delaying the release of its October-December earnings for a second time as it probed the embarrassing allegations, with fears growing that the pillar of corporate Japan could be delisted from the Tokyo bourse.