Clean energy is another area that investors need to watch out for potential bankruptcies. Several publicly-traded and private solar firms have gone belly up recently, led by the high-profile blow-up of government-backed Solyndra. One clean energy stock that short sellers are ogling is KiOR ( KIOR), which aims to convert biomass into fuel oil. To make that happen, KiOR is pouring huge sums of money into its facilities to generate meaningful production. The company's technology is said to be very promising, which is why shares rose from their mid-teens IPO last summer to above $20 by late September. Shares are now below $10 and could be headed even lower as investors start to realize that more money will be needed to see this company through to eventual profitability. KiOR's first plant will likely come on line this summer, and a second plant is expected to be running by the end of 2013. Meanwhile, cash flies out the door. KioR likely lost around $50 million in 2011, and analysts think losses could reach $100 million in 2012 and 2013, thanks to heavy spending on new plants. The company currently has $150 million in cash and the well could run dry by the end of this year unless KiOr can raise a lot more money. It needs upwards of $100 million more just to get its two plants going and reach profitability, and that assumes no glitches. KiOR's survival will hinge on oil prices. Its technology is uncompetitive when oil trades below $76 a barrel. So the company needs to see the current lofty prices for oil (which was recently just above $100 a barrel) to stay in place for the company to attract fresh investors. If KiOR waits too long, and oil prices pull back, it may find it impossible to raise cash. These companies aren't in deep distress now, but their balance sheets are weakening and more troubling times may lie right around the corner. To see these stocks in action, check out the Cash Burners portfolio on Stockpickr.