Monday was a strong day on Wall Street, with the Dow Jones Industrials and S&P 500 hitting record highs on new optimism from market participants. The technology sector, which has gotten hit hard recently, bounced back from its losses, and continued strength from other pockets of the market helped add to the overall enthusiasm among investors. Some comments from a Federal Reserve official suggested that tightening monetary policy would continue, but investors seemed to take that as a sign that the U.S. economy would remain strong. Moreover, solid performance from key individual stocks helped bolster market sentiment. Valeant Pharmaceuticals (BHC -1.48%), Rite Aid (RAD -27.27%), and Novadaq Technologies (NASDAQ: NVDQ) 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.

Valeant welcomes John Paulson

Shares of Valeant Pharmaceuticals climbed more than 6% after hedge fund investor and major shareholder John Paulson took a spot on the beleaguered company's board of directors. The move brings the number of directors on Valeant's board to 11, and CEO Joseph Papa lauded the move, noting that Paulson's "experience will be especially valuable as we continue to execute on our transformational strategy to turn around Valeant." Paulson said that he supports Valeant's plan to rebuild "core franchises in ophthalmology, dermatology, and gastroenterology while simultaneously using the proceeds from the sale of non-core assets and operating cash flow to de-lever the company." Given Paulson's holdings in the stock, it's unclear how the move materially changes the situation at Valeant, but shareholders took the new board director's addition as another step toward hoped-for recovery.

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Rite Aid keeps waiting

Rite Aid stock jumped 12% as speculators tried to guess what the Federal Trade Commission's final decision will be in the companys proposed merger with Walgreens Boots Alliance (WBA -1.12%). Earlier this month, investors sold off shares of the drugstore chain on fears that the merger simply would never get FTC approval. Yet some investors have started to look at what Rite Aid might look like if the deal falls apart, and today's assessment from those following the stock doesn't seem to be as pessimistic as it once was. With a regulatory deadline coming in the next month, shareholders won't have to wait much longer before they'll finally get an answer to the long-standing question, which has remained unresolved since Walgreens first made its bid to buy Rite Aid back in 2015.

Novadaq gets an offer it can't refuse

Finally, shares of Novadaq Technologies soared 95%. The fluorescence imaging specialist got a buyout offer from Stryker (SYK -0.85%) for $701 million, under which Novadaq shareholders will receive $11.75 per share in cash for their stock. Novadaq CEO Rick Mangat was ecstatic about the deal, noting that the company's SPY and PINPOINT technology has represented a big step forward for minimally invasive surgical procedures. Investors had been worried about sluggish financial prospects for Novadaq, but Stryker believes that the acquisition will help it "do more by enhancing cross-specialty surgical visualization." Even with the huge premium, however, the buyout price represents less than half of Novadaq's all-time high in early 2014.