What happened

Shares of Stratasys (SSYS 0.83%) went stratospheric on Friday, closing the day up 14.4%.

There's just one problem: No one seems to know why.

What I can tell you is that there don't appear to be any positive catalysts for the move. No one upgraded the stock today. No analysts changed their price targets. The company didn't issue any press releases or Securities and Exchange Commission filings -- and isn't due to report earnings again for at least another month.

Nor is Stratasys' move higher due to some enthusiasm for 3-D printing stocks in general. While peers such as 3D Systems, Protolabs, and Materialise also closed the day higher, none of them had nearly as good a day as Stratasys did.

3-D printer

Image source: Getty Images.

So what

What caused this giant leap in Stratasys stock, on no news whatsoever?

I wouldn't make anything of it. If there's some news out there that someone is trading on -- which sparked a reaction among momentum traders -- that news will come out in fairly short order, and we'll finally know the "why" of what happened today.

And if not -- the stock will eventually give back its gains.

Now what

Stratasys is still unprofitable after six years of trying. Its forward P/E ratio is 60 (assuming it does finally turn a profit next year), and its ratio of price to free cash flow is over 50.

I wouldn't be in any hurry to own it.