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.

Matthew Frankel has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.