Quite a nice day for Tellabs (TLAB), which jumped 64 cents, or 12.3%, to $5.84 in Thursday’s trading. There was no news on the stock, and the only research item I came across was a brief note from Morgan Keegan’s Simon Leopold on the communications sector; he wrote that he sees “material challenges for Tellabs to grow in 2008.” Not the stuff from which dreams are made.

On the other hand, Tellabs is an oft-mentioned takeover target, and I would not be surprised if speculation resurfaced again today. I would also note that the stock has been fairly ugly lately, and trading at levels not seen since 2002; the company has zero long term debt, and almost $4 a share in cash, about two-thirds of its market cap.

A spokesman for the company said Tellabs announced no news today, and had seen no research other than the Morgan Keegan note. He also said he has heard no rumors today.

I would also note that volume totaled 28.5 million shares, more than triple the daily average turnover. According to trading data I just pulled from Yahoo Finance and sorted in Excel, it was among the 20 heaviest trading days in the stock since 1990.

If you have other theories, please pass them along.