DOW CLOSES AT ALL-TIME HIGH AGAIN: Here's what you need to know

Stocks were mixed to start the week during trading on Monday, with the Dow finishing in the green and Nasdaq in the red - a common post-election theme.

The Dow also set another closing record, the 15th record mark since the election.

We've got all the headlines from the day, but first, the scoreboard:

First, the scoreboard:

• Dow: 19,791.25, +34.40, (0.17%)
• S&P 500: 2,256.70, -2.54, (0.42%)
• Nasdaq: 5,411.98, -32.10, (-0.59%)
• US 10-year yield: 2.479%, +0.015

1. Trump tweet send Lockheed Martin sliding. President-elect Donald Trump tweeted that Lockheed's F-35 was too costly, sending the stock down by as much as 5% during trading. It closed down a little more than 2%.
2. Trump picked Gary Cohn, Goldman Sach's COO, for a spot in his administration. The pick of Cohn to head up the National Economic Council was first rumored on Friday. It also makes Cohn the third Goldman alum to be a part of Trump's administration.
3. Valeant got some bad news and tumbled. The generic version of the troubled pharma giant's heart drug Nitropress was approved by the FDA on Monday. The news sent the stock lower by almost 5%.
4. Oil companies surged after news of an agreement between OPEC and non-OPEC producers for a production cut. The oil producers jumped between 2% and 5% after news that the oil cartel and outside countries had agreed on a deal.