Did I blow it? Barely a month ago, I was chiding investors for panic-selling shares of EMC (NYSE:EMC) after the company reaffirmed guidance at its annual analyst day. Today, I'm feeling stupid. The storage-systems maker said this morning that Q2 sales and earnings would land noticeably below its own estimates.

Shares of EMC are trading roughly 4% lower as I write, and unlike before, I now find myself sympathizing with those running for the hills. Why change my tune? Management. Just 32 days ago, the top brass was telling the world it would book at least $2.66 billion in sales during Q2. Now that total has been revised to $2.575 million, leaving an $85 million gap. (Those funds actually fall into Q3 sales, if you believe the press statement.)

Earnings will also come in light. EMC's earlier forecast called for $0.13 per share in GAAP net income. Today, the company says it's more likely to earn $0.12.

To be fair, EMC is still growing, with billions in the bank, and it's still the leader in a high-growth industry. But I wonder whether this miss, which management blames on an inability to meet demand for its storage systems, isn't a sign of the inefficiency that sometimes comes from acquisitions. EMC has made plenty of good buys over the past two years.

Or perhaps it's that EMC is having a harder time beating back tough competition. Storage is a very crowded market, dominated by EMC, IBM (NYSE:IBM), Hitachi (NYSE:HIT), and Network Appliance (NASDAQ:NTAP). But as EMC has moved into software, it has expanded its list of potential competitors, including Hewlett-Packard (NYSE:HPQ) and CA (NYSE:CA) in network management. A growing field of well-financed rivals isn't likely to be good for margins. (Though, to be fair, EMC has faced down big threats many times before.)

Frankly, it's one thing to come short of analyst arm-waving. It's another to set the bar high on your own, then run through the hurdle. That's what EMC did. Maybe that's why Chief Financial Officer Bill Teuber said his team "had more work to do" in qualifying his Q2 projections at analyst day. Back then, investors sold while I scoffed. Nobody's laughing now.

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Fool contributor Tim Beyers didn't own shares in any of the companies mentioned in this story at the time of publication. You can find out what is in his portfolio by checking Tim's Fool profile. The Motley Fool has an ironclad disclosure policy.