Once a month, many retailers report their monthly same-store sales and net sales data. Unfortunately, investors may now have to wait a lot longer to get an idea of how their retail stocks' businesses are faring. Teen retailers Aeropostale (NYSE: ARO), Abercrombie & Fitch (NYSE: ANF), and American Eagle Outfitters (NYSE: AEO) have all stopped reporting their same-store sales figures on a monthly basis.

Same-store sales, or comparable-store sales, reveal sales growth (or lack thereof) for stores that have been open for more than a year. They can help investors discover how a retailer's currently faring in its drive to attract customer traffic, hint at broader retail trends, and provide illuminating comparisons to previous sales figures.

The monthly report can be a fairly silly day for retail stocks, since they often react in highly dramatic (if not downright nonsensical) ways to those short-term metrics. Unfortunately, as a result, there may be a growing tendency for retailers to simply avoid the monthly disclosure altogether.

These teen retailers aren't alone in curtailing their disclosures. They join a rather large crowd of retailers that wants out of the monthly comps fray. Five years ago, Thomson Reuters tracked monthly data from 68 retailers; now, that number's a mere 25.

Back in 2006, Starbucks (Nasdaq: SBUX) decided to stop disclosing its comps on a monthly basis. It was following retailers like Wal-Mart (NYSE: WMT) and Talbots (NYSE: TLB), which had changed to quarterly same-store sales disclosures instead.

I doubt many Foolish investors agree that less is more where investing data's concerned. Although retail stocks do become volatile on that fitful disclosure D-Day (the first Thursday of every month), true long-term investors know that one month's worth of data is only one piece of a lot of information that should be weighed before making a buy or sell decision.

The dwindling number of retail chains that still report the figure on a monthly basis isn't good news for investors. Now more than ever, we need more transparency and pertinent information in the marketplace, not less.

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