BOSTON, Aug 19 (Reuters) - Hedge fund manager Quentin Koffey has left Senator Investment Group, where he spearheaded the firm's activism strategy for two years, and plans to launch his own firm in the future, Senator and Koffey said on Thursday. "Quentin's constructive approach to activism yielded exceptional results for Senator and we look forward to investing in his next venture," Senator's co-founder and managing partner Doug Silverman told Reuters in a statement. At Senator, Koffey was best known for having teamed up with Cannae Holdings to bid https://www.reuters.com/article/us-corelogic-cannae-senator/cannae-holdings-hedge-fund-senator-investment-group-bid-for-corelogic-idUSKBN23X2R1 for property data and analytics company CoreLogic last year.