He suspended withdrawals from his flagship Tudor BVI Fund ( -5% on the year as of November ) so that he could split the toxic assets out of his $10 billion flagship hedge fund from everything else.
He needs to do this because investors were trying to redeem 14% of the Tuydor BVI Fund at the end of the year. He is not able to do so without leaving the remaining investors in the fund holding too large of a proportion of illiquid assets, particularly corporate credit in emerging markets.