You’ll often see all of the same companies within a similar sector trade in tandem. That’s why many investors buy stock in company B after their rival, company A, blew past estimates. But that logic failed to hold for investors in Hutchinson Technology (Nasdaq: HTCH), which supplies subcomponents to disk drive makers such as Seagate Technology (NYSE: STX) and Western Digital (NYSE: WDC). Those firms are seeing robust demand, as we previously noted. But Hutchinson had some manufacturing glitches that led its customers to shift business to other vendors, leading to an unexpected loss and a -20% swoon in its shares.

Although management insists that Hutchinson’s problems are short-term in nature, shares are likely to stay in the penalty box for at least a few more quarters. If you want exposure to the disk drive sector, you may as well stick with the names noted above, as they are also inexpensive when judged by traditional valuation metrics.

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Whither our love affair with the buffalo wing? Even the most diehard fans of the ubiquitous pub grub need to take a break, and they did that in droves, as same-store sales at Buffalo Wild Wings (Nasdaq: BWLD) fell a few points in April, and foot traffic fell by more than -5%, from a year ago. That sent shares, which have long been favored by momentum investors, into a tailspin today, falling roughly -20%. That’s great news for short investors, who had held nearly a quarter of the company’s shares, according to recent data.

Even after the price plunge, shares still don’t look cheap, trading at more than 20 times likely 2010 earnings per share of around $1.90. To once again garner a loftier earnings multiple, management would need to deliver plans for renewed growth in store openings and same-store sales. And that may prove difficult in light of the near saturation of neighborhood bars selling buffalo wings.

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Unisys (NYSE: UIS) is giving us another lesson in trading strategies. Shares sharply fell Tuesday as quarterly results badly missed forecasts. A sudden drop tends to bring out value investors in the next trading session on hopes that the selling is done. But many times, it can take a large fund several days to exit an investment, which appears to be happening with Unisys. After falling -20% Tuesday, shares opened slightly higher this morning, but have been in freefall ever since and are now down more than -5%. Shares could remain under pressure until the current shareholder base of technology investors washes out and the new base of value investors rolls in. And that could take some time.