Jeff Altman’s Owl Creek Asset Management is pushing Brunswick Corp. to spin out its fitness business after building an activist stake in the company, which also makes boats and billiards tables. "Brunswick stakeholders would benefit significantly from a spinoff of the fitness equipment business," the event-driven hedge fund said in a letter addressed to the company’s board. "The marine segment on a stand-alone basis is worth more than the current valuation for all of Brunswick, implying the market assigns negative value to the fitness segment."