Some Valley investors succeed by spotting good ideas and nurturing them. Some succeed through utter ruthlessness. In that latter category lies Sequoia Capital, the investor behind Apple, Cisco, Yahoo, and Google. Skyrider, a file-sharing startup which had raised $25 million or more in venture capital, has shut down , according to VentureBeat. Startups fail all the time. But Skyrider was backed by Sequoia — and Sequoia, which zealously guards its reputation, rarely lets startups die so visibly. Skyrider was started as an ad-supported file-sharing service; its homepage suggested it was shifting into content distribution. But BitTorrent, a far better known name in file sharing, has struggled to crack that market. What's telling about Skyrider's failure:Sequoia, which recently summoned the CEOs of startups it invests in to an emergency meeting and told them to cut costs, is doing the same with its own portfolio. Rather than continuing to invest in the losers, it's culling the herd now. This despite the fact it just raised $1.7 billion in new funds — money that's destined for new ideas, not old ones . AlwaysOn founder Tony Perkins, my old boss at the Red Herring , has a trenchant analysis of Sequoia's message to entrepreneurs, disguised only thinly as satire. His point, as a longtime observer of Sequoia, is that the venture capital firm's sudden panic is as much about its partners' losing face in front of their investors — the endowments, pension funds, and wealthy individuals from which they raise funds. Appearances matter, now more than ever. And if keeping up appearances means dropping a company? Sequoia's newly hungry partners will do it in a heartbeat.