 Alliancebernstein L.P. boosted its stake in W. R. Berkley Corp NYSE:WRB by 1.3 during the 1st quarter, according to its most recent Form 13F filing with the Securities and Exchange Commission SEC. The firm owned 236,933 shares of the insurance providers stock after buying an additional 3,084 shares during the period. Alliancebernstein L.P. owned 0.13 ... 