Shares in IBM plunged more than 25% on Tuesday after the US tech giant released disappointing preliminary second quarter results. IBMs stock was on track for an even steeper single day decline than it suffered during the 1987 “Black Monday” crash. IBM had issued a profit warning and blamed shifts in corporate customers spending. The company said revenue for the three months ending in June came in at $17.2bn, up just 1% year over year. The company said it had “faltered” in keeping pace with a...