Investors pulled more than $3 billion from Brevan Howard's main hedge fund in the first half of the year, a source told Reuters on Tuesday. The outflows, which came during a torrid six months for many firms, took the fund's assets down to $15.7 billion, the source said - a near halving of the fund's total assets three years ago at $28 billion. News (Other OTC: NWSAL - news) of the slide in assets was first reported by the Wall Street Journal on Tuesday.