Well, well, what do you know? At long last, the data seems to be bearing out my longstanding hunch that high-flying small-cap stocks are cruising for a proverbial bruising. Never mind that I've had that hunch for at least two years. It's finally true!

Want proof? Fair enough: Over the past three months, the large-cap-dominated S&P 500 -- an index that's home to such market stalwarts as Microsoft (NASDAQ:MSFT), McDonald's (NYSE:MCD), and Time Warner (NYSE:TWX) -- has outperformed the Russell 2000 (a small-cap bogey that currently includes Skyworks Solutions (NASDAQ:SWKS) and RF Micro Devices (NASDAQ:RFMD) in its lineup) by roughly 5 percentage points!

Impressive, no?

Now wait a minute ...
OK: Five points in three months does not an investment case make. Still, the market really does move in cycles. And while it sometimes seems to take an eternity for investors to catch up with valuation reality, it's not hard to suspect that that's precisely what's happening right now.

After all, when major players the likes of Medtronic (NYSE:MDT) and Texas Instruments (NYSE:TXN) -- long-haul overachievers both -- trade with price-to-earnings ratios that clock in well below their respective industry averages, even "efficient market" true believers will probably agree that we're in the presence of at least some measure of valuation slack.

Zig when others zag
If history's any guide, it's only a matter of time before Wall Street catches the drift and lurches, rather than tiptoes, in the direction of large caps. But make no mistake: That will be great news for small-cap investors. No, seriously.

If you've done your homework and invested in up-and-comers with rock-solid fundamentals and sound business plans, a sell-off will provide a fine time to contemplate dialing up your stake. It's when high-quality stocks of any size languish because of market sentiment -- rather than fundamentals -- that savvy investors can positively smell the opportunity.

The dog ate my homework
If, on the other hand, maybe you haven't quite finished your homework -- hey, it's been known to happen to the best of us -- the Fool is here to help: A completely free 30-day guest pass to Tom Gardner's Hidden Gems small-cap investment service is just a mouse click away. If you want to zero in on smaller-cap concerns that have what it takes to get the market-beating job done, I encourage you to give Hidden Gems a whirl -- for free. Just click here to get started.

Shannon Zimmerman runs point on the Fool's Champion Funds newsletter and co-advises GreenLight, a Fool service designed with investing newbies in mind. At the time of publication, Shannon didn't own any of the securities mentioned above. Microsoft is an Inside Value recommendation. Time Warner is a Stock Advisor pick. You can check out the Fool's strict disclosure policy by clicking right here.