Updated from 12:46 p.m. ESTOn, Oct. 1, NYSE Euronext ( NYX) completed its acquisition of the American Stock Exchange, founded in 1842, now called NYSE Alternext U.S. The exchange has more liberal listing policies than the NYSE or the Nasdaq, so it tends to trade smaller to mid-size stocks, which are more volatile. Many of these stocks have been heavily shorted and significantly depressed, creating Amex stock-squeeze opportunities. A short squeeze takes place when short-sellers quickly cover their bearish positions on optimistic news, which can move the price of the stock up sharply. The metric for measuring short-squeeze opportunities is the short ratio, also known as the "days-to-cover ratio," which is the number of days it would take the short-sellers to cover their positions based on recent average daily volume of the stock. One Amex stock with a very high short ratio is Park National ( PRK), an Ohio-based multibank holding company, which has a short ratio of 23.7. This means that it would take more than 23 days for the short-sellers to cover their positions on the stock. To read more, visit Stockpickr.com. Thursday, Park National closed at $63.05 per share, down over 2% year-to-date.