U.S. markets continued friday's session’s decline tonight , with the Nasdaq Composite looking at its biggest losses since early February.The Nasdaq Composite dropped 74 points, or 1.7%, with biotechnology and social-network stocks leading the losses on the index. The S&P 500 index fell 15 points, or 0.8%, to 1,851.34, within a hair’s breadth of a support level of 1,850. Health-care stocks led the losses on the benchmark index.The Dow Jones Industrial Average dropped 74.47 points, or 0.4%, to 16,231.18.