Investors got hit on the head yesterday, when a key Apple supplier issued a gloomy earnings forecast. It cited an unnamed customer. Since last fall, Apple stock has underperformed both gold and the economy of Greece. What gives?

“Wall Street was expecting everything to go perfectly for Apple. We’ve now had little bits of bad news and unexpected news, like the iPhone 5 — not as much earth shaking product as people thought,” says Henry Blodget at Business Insider. “You have competitors coming into the market whose products are equaling Apple’s.”

That’s code for Samsung. Its new smartphone is out later this month. Blodget thinks the fantastically profitable iPhone is near the end of its life cycle. And the question, as always, is what’s Cupertino got next?

Some analysts whisper that Apple’s R&D folks are unprepared for a tech future of big data and artificially intelligence — a hint of how unfashionable the company’s become, for now.

In the past five days, Apple’s stock price has plunged from over $430 to $395, falling significantly yesterday when a key supplier issued a gloomy earnings forecast.

Over the past year, Apple’s stock has had a bumpy ride. Since hitting a peak last fall, its value has slid by 40 percent.