With the market hitting fresh highs on a regular basis, it seems most American companies are doing quite well. However, even in the vastly improved economy, there are still some companies struggling to stay alive. Some are obviously in trouble, like Radio Shack (NASDAQOTH:RSHCQ), which can't seem to downsize its operations fast enough, and Sears Holdings (NASDAQOTH:SHLDQ), which hasn't turned a profit in years.

Then again, some are not so obvious, like Zynga (NASDAQ:ZNGA). Here are six companies that could have serious trouble making it until the end of 2014, as well as what's going wrong and what would need to happen for a turnaround to take place.