The stock market sagged after the Obama administration ratcheted up the pressure on Syria. Secretary of State John Kerry said there was undeniable evidence of a large chemical weapons attack in Syria last week and suggested the administration was edging closer to a military response. Stephen J. Carl, head equity trader at Williams Capital, said the market was drifting until Kerry’s televised talk jolted stocks. But corporate deals helped give the market a lift early on. Amgen (up 7.7%) is buying Onyx Pharmaceuticals (up 5.6%) for $10.4 billion. And TMS International (up 12.3%) is being sold to members of the Pritzker family.