Investor George Soros's family fund bought about $2 billion of European bonds formerly owned by MF Global Holdings Ltd., the debt that helped force the securities firm to file for bankruptcy protection Oct. 31, according to people close to the matter. Under the direction of MF Global's former chief executive, Jon S. Corzine, the firm accumulated $6.3 billion of short-term debt issued by various European nations, mostly from Italy, in a bid to boost trading profits. Over the summer, this debt led to nervousness by investors, regulators and ratings companies, resulting in the firm's collapse just over a month ago.