SAN FRANCISCO (Reuters) – San Francisco-based 137 Ventures said it raised $137 million for its second fund, underscoring the eagerness of investors to buy shares in start-ups before they hold initial public offerings. The firm, which buys private-company shares from company founders, early employees, and other investors, counts companies such as data-analytics business Palantir, space-exploration firm SpaceX and blog site Tumblr among its portfolio. Tumblr sold to Yahoo! Inc last year for $1.1 billion. …