One stock that's seen some big insider buying recently is Nanosphere ( NSPH), which develops, manufactures and markets an advanced molecular diagnostics platform, the Verigene System, that enables sensitive genomic and protein testing on a single platform. Insiders are finding some deep value here since the stock is down over 58% so far in 2011. This company has a current market cap of $50 million and an enterprise value of $21 million. This is a cash-rich company, with $30 million in cash on its balance sheet and zero debt. The U.S. Food and Drug Administration said on June 21 that it would not approve Nanosphere's Plavix Metabolism diagnostic test until the company submits additional data. Following that news, the stock plunged from around $2.30 to its current price of $1.80 a share. A director just bought 285,000 shares, or $459,201 worth of stock, at $1.57 to $1.64 per share. This same director also bought 2,700,000 shares, or $5.94 million worth of stock, at $2.20 back on May 10. From a technical standpoint, this stock has been crushed so far this year, falling from a high of $5.54 to its current level of $1.80 a share. This stock is now trading below both its 50-day and 200-day moving averages, which is bearish. That said, NSPH recently hit a short-term bottom at $1.46, and upside volume has been expanding dramatically. One big up day last week saw volume of 6.4 million, which is well above the three-month average volume of 489,000 shares. >>Practice your stock trading strategies and win cash in our stock game. If you're looking to buy this stock, I would add this name on any weakness with a stop just below $1.46 a share. I would only add to a long position if you see NSPH trade back above its 50-day moving average of $2.37 a share on strong volume. It's worth noting that NSPH has a reasonable short interest of 7.7% of the float. The bears have increased their bets from the last reporting period by 5.4%, or by around 109,000 shares.