The stock market continued its run upward on Monday, responding favorably to positive comments over the weekend that suggested that the Republican tax plan is likely to get through Congress and become law before the end of the week. The Nasdaq Composite climbed above the 7,000 level for the first time ever, and the Dow and S&P 500 responded with gains of more than half a percent as well. Some individual companies' shares did far better than that, and Twitter (NYSE:TWTR), Akamai Technologies (NASDAQ:AKAM), and Boyd Gaming (NYSE:BYD) 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.

Twitter has analysts looking for more gains

Shares of Twitter jumped 11%, following up on a stellar performance over the past several months as investors reacted favorably to an upgrade from analysts at JPMorgan. The Wall Street giant boosted its rating on the social-media giant from neutral to overweight, and pushed its price target higher by 35% to $27 per share. Analysts pointed to improving video and live-stream content, as well as recent changes to the service's timeline and notifications. JPMorgan expects daily active users to climb 10% in 2018, helping to push Twitter to a profit, and investors are excited about the idea that Twitter could finally be starting to take off.

Repeated instances of TWTR ticker with up arrows.

Image source: Twitter.

Akamai gets buying interest

Akamai Technologies stock climbed 14% after the internet efficiency specialist attracted the interest of a well-known activist investment company. Investors at Elliott Management reported having taken a 6.5% stake in Akamai late Friday, and many analysts following the stock cited the move as likely having a positive impact on the company and its share price in the immediate future. Some believe that Akamai is ripe for a takeover from a larger technology company, although somewhat downbeat guidance for its core business suggests competitive threats that might dissuade a would-be buyer. Elliott Management might well be enough to turn the tide, and shareholders today are expressing their hope that that will be the case.

Boyd makes a buy

Finally, shares of Boyd Gaming gained more than 7%. The casino company announced early Monday that it had agreed with industry peer Penn National Gaming (NASDAQ:PENN) to acquire four casino resort operations in connection with Penn's pending acquisition of Pinnacle Entertainment. Boyd will pay $575 million for the Ameristar St. Charles and Kansas City operations in Missouri, as well as Indiana's Belterra Casino Resort and the Belterra Park property in Cincinnati. The deal should make it easier for Penn National's Pinnacle merger to go forward, and it marks a great opportunity for Boyd to diversify its geography, grow its customer base, and continue positive momentum from earlier in the year.