NEW YORK ( TheStreet) -- MF Global Holdings ( MF), a foreign exchange and derivates brokerage, is among the biggest market winners on Wednesday, with a 12% gain at midday. After the market closed on Tuesday, MF Global announced that it had hired former New Jersey Governor and Goldman Sachs ( GS) head John Corzine as its chairman and chief executive, effective immediately. On Wednesday, more than 13 million shares of MF Global were traded at midday, versus an average daily volume of 1.5 million shares. After the announcement, MF Global's stock popped more than 11% to $7.32 in the after-hours session Tuesday. Current CEO Bernard Dan has resigned from MF Global for "personal reasons," the company said in its statement announcing Corzine's hiring. Corzine's contract includes an initial base salary of $1.5 million; a sign-on bonus of $1.5 million; a target cash bonus of $3 million for the fiscal year ending March 31, 2011 -- based on individual and corporate performance goals and subject to a minimum bonus of $2 million; and a stock option to purchase 2.5 million shares of MF Global common stock. Analysts are divided on the outlook for MF Global, with the harshest assessment coming from the debt side of the research universe. Alexander Yavorsky, an analyst at Moody's Investors Service, indicated that Corzine has his work cut out for him. In a note Tuesday afternoon, the Moody's analyst said potential concerns about the unexpected nature of the leadership change are "tempered by Mr. Corzine's decades of first-rate industry leadership." Still, Yavorksy said, MF Global remains a long way from having its problems solved.