Stocks started weak but finished with gains Monday. The S&P rose 0.3%, while the Dow Jones industrial average edged up 0.1%. Both scored new highs. Although it didn’t hit a new high, the tech-heavy Nasdaq rallied 0.6%. Chips, security software and biotechs gave strong showings. Apple (AAPL), which makes up almost 8% of the Nasdaq, rose 1%. In a letter to CEO Tim Cook, activist investor Carl Icahn wrote that Apple’s stock is worth 240 a share.