Over the weekend, investors who tuned into 60 Minutes got a look at the new Michael Lewis book on high-frequency trading, with dire conclusions about how traders take advantage of both institutional and individual investors. Yet even with that backdrop, stocks gained ground Monday, as bullish comments from Fed Chair Janet Yellen were enough to lift investors' spirits. With the broader market up 1%, gains in Exact Sciences (EXAS -3.97%), Builders FirstSource (BLDR -2.88%), and Clayton Williams Energy (NYSE: CWEI) looked especially strong today.

Exact Sciences climbed 10% after a positive story in Barron's highlighted the company's colon-cancer screening test, Cologuard. With Cologuard having gotten a unanimous recommendation from an FDA advisory committee last week, investors are increasingly hopeful that FDA approval won't be too far behind. The advantage of the Exact Sciences test is that it's far less invasive than a full colonoscopy, yet the ability for safe and effective detection of a major type of cancer appears to be extremely strong. With a great deal of demand for innovative solutions for detecting diseases, Exact Sciences has further room to climb if its test earned the FDA's positive nod.

Image credit Flickr/Lindsey G.

Builders FirstSource gained 13% after analysts at Deutsche Bank upgraded the maker of structural building products to builders of new homes. Although homebuilder stocks have struggled lately under fears that higher interest rates would eventually slow the rise in home-buying activity, many believe that they've declined to the point at which the stocks look favorable from a long-term perspective. Given the long-run need for more housing, both in the single-family and multi-family arenas, Builders FirstSource is a good second-derivative play on the homebuilders. If the builders thrive, then Builders FirstSource should see its business improve as well, and that could spell bigger gains for shareholders in the future.

Clayton Williams Energy rose 15% after analysts at SunTrust boosted their price target on the independent oil and gas company by $25 per share to $170. Clayton Williams operates primarily in Texas, Louisiana, and New Mexico, with exposure to promising areas that include the Permian Basin. With other companies in the area having had success with their operations, investors are growing more optimistic that Clayton Williams could follow suit and deliver stronger growth in the near future.