Fortress Investment Group LLC (NYSE:FIG) disclosed that it had purchased $20 million worth of Bitcoins in a recent Securities and Exchange Commission filing (h/t Saumya Vaishampayan at MarketWatch), but its investment has already lost value, dropping to $16.3 million as of December 31, 2013, which means that it’s approaching $10 million now if Fortress has held onto its position (unless they left their Bitcoins deposited with Mt. Gox, of course). Fortress mentioned Bitcoin investment last year Fortress Investment Group LLC (NYSE:FIG) director Michael Novogratz hadn’t kept his Bitcoin investment a secret, but when he first mentioned his interest in Bitcoins they…