Stocks climbed Tuesday to extend a weeklong rebound and remove some more gloom from the market. The Nasdaq led with a 0.7% advance. Biotechs were a source of strength on the composite index for a third straight day. The S&P 500 climbed 0.4%, aided largely by an energy sector that rallied despite an international agreement that eventually lets Iran put more crude oil in the global market. But transportation stocks suffered.