(Updated with American Eagle Outfitters monthly sales announcement.)NEW YORK ( TheStreet) -- American Eagle Outfitters ( AEO) ( ANF) is piggybacking off rival Abercrombie & Fitch, announcing on Thursday that it will refrain from reporting monthly sales results come 2011. The news comes after Abercrombie & Fitch announded earlier in the month, following lackluster October results, that it too will no longer report monthly same-store sales numbers starting next year. Neither Abercrombie & Fitch nor American Eagle provided a reason for their decision. The move to discontinue reporting monthly figures is in vogue with retailers, who are exposed to wild swings in their stocks after the numbers are released. Retail giant Wal-Mart ( WMT) stopped reporting monthly sales back in June, while Children's Place ( PLCE) and American Apparel ( APP) also went mum in earlier this year. Sears ( SHLD), Home Depot ( HD), Lowe's ( LOW) and Chico's ( CHS) are also among the companies that no longer report monthly same-store sales. Currently, in fact, comparable sales reports only represent about 10% of total U.S. retail sales, according to Customer Growth Partners. "The monthly reports Wall Street so breathlessly awaits really primarily portray only two retail sectors, apparel chains and department stores, each of which represent well under 3% of U.S. personal consumption expenditures," Craig Johnson, president of Customer Growth Partners said in a statement earlier in the year. "As we have stated for some time, refraining from monthly comp reporting is a good way to align how management thinks about the business to the interest of long-term shareholders," Wall Street Strategies analyst, Brian Sozzi, wrote in a note. Retailers are not required to report monthly sales and it's an expense to do so. For apparel retailers, in particular, it often adds significant volatility in the stock if a month of weather or calendar shift if friendly or unfriendly, Sozzi notes. "Specifically to American Eagle, it has been undergoing a fundamental change to planning and allocation that began in fall 2009, a process that does not produce results overnight, and earlier in the year led to inconsistencies in the business," Sozzi continued. Despite the shrinkage in the number of companies that report monthly same-store sales numbers, the extent to which investors scrutinize these numbers has increased. Today alone, the S&P Retail Index is currently up 1.5% to 480.22, with stocks like Gap ( GPS), Zumiez ( ZUMZ) and Ross Stores ( ROST) all rallying about 5% on their results. But how good of a gauge on the health of a company are these numbers, really? The two biggest factors contributing to same-store sales upside and downside are price and the number of customers who purchase merchandise. Thus, if prices go up and the number of transactions remains the same, comparable sales will increase, and vice versa. Any time comparable sales rise it means shoppers are either buying more or spending more -- or both, which, of course, is a good sign. But when retailers offer discounts and shoppers close their wallets, as seen during the economic downturn, same-store sales can take a major beating.