Roughly two months ago, I announced that I'd be selling my shares in Escala (NASDAQ:ESCL), the leading international coin and stamp trading house, over concerns I had regarding its relationship with AfinsaBienes Tangibles, the Spanish collectibles company that happens to be Escala's majority owner.

At the time, a spate of negative media reports suggested that something fishy was afoot with the company. I even asked whether Escala, or more appropriately Afinsa, was a "glorified Ponzi scheme." Some shareholders, myself included, wondered whether there was an effort by short sellers to undermine the stock. Some even accused me of being part of the cabal, or at least on the payroll.

While I concluded that the companies were not engaged in any untoward business, I announced my intention to sell anyway, because I was uncomfortable with Escala's dependence upon its parent. Afinsa owns 72% of Escala, and accounts for 86% of its sales and 70% of its profits. I surmised that a whiff of a problem at Afinsa would barrel down against Escala. Due to the Fool's strict disclosure and trading policies, I was unable to sell my stock for 10 days after the story appeared.

So how has Escala been faring over the past two months without my ownership stake? Just fine, thank you very much. The stock, which had dipped below $15 a share as my article appeared, closed yesterday at more than $28. It reached as high as $30 a share in intraday trading. The company has scheduled nearly two dozen major stamp auctions for the second half of its fiscal year, and it's an official auctioneer for the Washington, D.C. 2006 World Expo. When it last participated in such an event back in 1997, it raked in more than $10 million. (That's a whole lot of stamps.)

Sure, I look back a little wistfully at my holdings and imagine what could have been, but I really don't regret selling. An important tenet of investing is that you should be able to sleep at night without worrying about your stocks. While Escala never kept me awake, it did make me question whether I was assuming too much risk in the event something went wrong. Fools have seen this happen occasionally with stocks; a company can get so reliant upon one product or customer that its business implodes when the product stops selling or the customer starts favoring a competitor.

Last summer, CantelMedical (NYSE:CMN), a Motley Fool Hidden Gems pick that manufactures infection control and diagnostic equipment, experienced just such a meltdown. Its Canadian distributor, Olympus America, had accounted for around 30% of Cantel's revenues. Olympus announced that it was terminating its distribution agreement with the company, and the formerly high-flying stock tumbled more than 40% on the news. It's had trouble regaining its footing since.

While the situations at Cantel and Escala are somewhat dissimilar, they do highlight the danger of relying too much on one source of revenues or profits. Should Escala's relationship with Afinsa turn sour, the stamp and coin trading outfit just might end up descending to new depths, rather than scaling new heights.

Trade up for some related Foolishness:

Fool contributor Rich Duprey does not own any of the stocks mentioned in this article. You can see his holdings here. The Motley Fool has a disclosure policy.