Gilead Sciences (NASDAQ: [[ticker:GILD]]) has brought back former top executive Kevin Young as chief operating officer. Young spent the past two years as an advisor to the Foster City, CA-based drug maker, and before that was its EVP of commercial operations for ten years. Young’s return fills a gap left by Paul Carter, who replaced Young two years ago. Gilead has also hired Martin Silverstein, a former management consultant, as EVP of strategy.