Tech stocks had a generally positive week last week, heading into the middle on June. But these three tech tickers ended up swimming against the stream, and not in a good way:

  • Hydrogen fuel cell producer Plug Power (NASDAQ:PLUG) gently swooned 5.5% lower, in spite of any obvious value-destroying news. When you're as hyper-volatile as Plug Power, those are the breaks sometimes.
  • NQ (NYSE:NQ), which provides mobile Internet services for Chinese customers, fell 15%. The memory of NQ's positive fraud investigation news from the previous week is fading -- and NQ investors are getting restless.
  • Finally, optical networking expert Finisar (NASDAQ:FNSR) plunged 20% in one terrifying night. Shareholders came into this report with high expectations, given the strong report from Finisar customer Ciena (NYSE:CIEN) the previous week. But fourth-quarter earnings disappointed, and management guidance didn't help to calm any nerves.

Two of these stocks seem destined for extreme volatility and uncertain long-term returns. The third one might be both undervalued and delicious.

Find out more in the slideshow below.