Kevin Kearns joined Loomis Sayles as a vice president and senior derivatives strategist, according to spokeswoman Erin Heggerick. It is a new position. Reporting to fixed-income CIO Jae Park, Mr. Kearns will lead the firms efforts to develop and implement investment strategies that incorporate credit default swaps and related derivative instruments. Mr. Kearns was director of derivatives, quantitative analysis and risk management at Boldwater Capital Management. Joseph H. Morgart, a managing partner and director of investor relations at Boldwater, said Mr. Kearns responsibilities were assumed by other team members.