Stillwater Mining (SWC) has agreed to an acquisition offer from South Africa’s Sibanye Gold (SBGL.) The proposed purchase price of $2.2 billion works out to $18.00 a share for the largest primary producer of platinum and palladium outside of South Africa and Russia.

The shares are trading at $17.42 as of 1:30 p.m.New York time on Friday. That price, slightly below the offer, indicates that the market isn’t anticipating a competing bid.

Stillwater Mining is a member of my Jubak Picks portfolio. The shares are up 52.7% since I added them to the portfolio on September 25, 2012.

I am going to hold the shares for a few days to see if, maybe, another bid emerges since Stillwater, as the only U.S. miner of platinum group metals, is a unique asset. But otherwise I will be selling the shares out of this portfolio next week.