What: Shares of Axiall Corp (NYSE:AXLL) jumped as much as 104% in early trading Friday after getting a buyout offer. As of noon EST, shares had settled slightly lower to an 85% gain on the day.

So what: Westlake Chemical Corp. (NYSE:WLK) disclosed that it offered $1.41 billion, or $20 per share, for Axiall Corp, only to have the bid rejected. The offer was for $11 per share in cash and 0.1967 shares in Westlake stock for each Axiall share.

It's not clear if Axiall's rejection is a tactic to try and get a better offer, or if the company has other plans, but today, investors are betting that the initial rejection won't be the end of this story. 

Now what: As an investor, I think now would be a wise time to take some chips off the table in Axiall Corp. Westlake Chemical has tried to buy it before, only to be rebuffed, and management could hold out again. That may sink shares again, so holding out for a better deal is a risk right now. I say it's time to take some of these massive gains today and run.