The stock market started the new week on a sluggish note Monday, and the broadest-based market benchmarks gave up ground as the Dow fell further away from the 20,000 mark. Even though the Nasdaq Composite climbed to new highs, a $2 per barrel plunge in the price of oil to fall below $53 weighed on sentiment. Even with the pause in the upward trend, some stocks posted solid gains, and Ariad Pharmaceuticals (NASDAQ:ARIA), VCA (NASDAQ:WOOF), and Exact Sciences (NASDAQ:EXAS) were among the best performers on the day. Below, we'll look more closely at these stocks to tell you why they did so well.

Vca Dogs
Image source: VCA.

Ariad gets an offer it can't refuse

Ariad Pharmaceuticals soared 73% after the cancer drugmaker announced it had agreed to an acquisition bid from Japan's Takeda Pharmaceuticals. Takeda agreed to a $24 per share cash bid for Ariad, which values the company at $5.2 billion when you take Ariad's enterprise value into account. Ariad CEO Paris Panayiotopoulos noted that the merger "will allow us to not only accelerate our mission to discover, develop, and deliver precision therapies to patients with rare cancers but also deliver meaningful value to our shareholders." Meanwhile, Ariad board chairman Alexander Denner also claimed his share of the credit for finding a buyer, noting that the deal "underscores the tremendous value that shareholder activism can create," and pointing to his Sarissa Capital as helping to make the deal possible. The companies expect the deal to be complete by next month.

VCA gets a treat

VCA climbed 28% after it too got an acquisition bid. Privately held Mars, which is best known for its M&M candy operation, agreed to buy the animal hospital company for $9.1 billion, paying $93 per share in cash for VCA. Mars also owns the Pedigree and IAMS pet food brands, so the deal feeds further into its strategic vision of building up its pet-care business. As VCA CEO Bob Antin said:

Mars has a long-standing commitment to pet health, wellness, and nutrition, [and] we will work together every day to continue to provide the quality care and excellent service VCA is known for to our clients and their pet families.

Pets are big business in the U.S., and investors can expect even more attention to be paid to the segment in the future.

Exact Sciences has healthy results

Finally, Exact Sciences gained 19%. The maker of the Cologuard colon-cancer screening test gave preliminary fourth-quarter results, predicting that it would report sales of between $34.9 million and $35.4 million. That would be up more than 140% from year-ago levels, and Exact Sciences said it performed about 82,000 Cologuard tests during the quarter, more than double what it did during the same period in 2015. Progress in getting new healthcare providers and insurance companies to embrace the test had Exact Sciences CEO Kevin Conroy proclaiming that, "Cologuard is becoming a standard of care for 80 million Americans who should be screened for colon cancer." Final results won't be available until February, but investors are convinced that Exact Sciences is on exactly the right path toward success.

Dan Caplinger has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.