Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares in Receptos (UNKNOWN:RCPT.DL) surged by as much as 10% today after announcing that it had completed enrollment in its phase 3 trial for the treatment of multiple sclerosis and amid chatter of a potential buyer.

So What: Receptos has been one of biotech's top performing stocks on optimism that its MS drug ozanimod could outperform Biogen's top-selling Avonex in late stage trials.

Receptos' RPC1063 is a once-daily drug that reduces the activity of autoreactive lymphocytes, or white blood cells, which are thought to be one of the causes of autoimmune disorders.

During phase 2 trials, ozanimod successfully achieved its primary endpoint of reducing the number of brain lesions in MS patients.

Receptos has indicated that it would like to find a partner to team up with on ozanimod, and, according to Bloomberg, interest may have expanded beyond licensing ozanimod to include a potential acquisition.

Now What: MS is a big and growing indication, and Biogen's Avonex is one of the top sellers in this $17 billion market, racking up $3.01 billion in sales last year.

If Receptos' phase 3 data is as good as its mid-stage data, then Receptos could file for FDA approval, and if that approval is granted, Receptos could end up with a blockbuster on its hands. Those are a lot of "ifs" so investors should approach this biotech with some caution -- especially since trial results from this study won't be available until 2017. That said, Receptos' potential opportunity could mean that it's a good option for speculative investors that are unfazed by the risk of a trial failure.