The answer is OptionsXpress (OXPS). They are the primary sponsor of the CNBC challenge and considering how many hits the site gets everyday with over half a million people enrolled in the contest, I believe OXPS will see a spike in subscriber growth and market share.
In fact, thestreet.com (TSCM) also started a similar challenge in April, sponsored by OptionsXpress. Looks like even more subscribers for OptionsXpress.
-- Faisal Laljee