A MANIC MONDAY: What you need to know on Wall Street

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Wow. What a morning.

The embattled Canadian drug company Valeant Pharmaceuticals is once again the dominant story on Wall Street. Here is quick recap of the news so far on Monday:

• Chief executive Michael Pearson is on his way out, and the company is looking for a replacement.
• Bill Ackman now has a seat on the board, and could push for asset sales.
• The company has accused its former chief financial officer of "improper conduct."
• That executive has rejected the accusation and refused to step down from the board
• The company has determined that "the tone at the top" and the "performance-based environment" may have had a part to play in the company's improper revenue recognition.

In other news, it has been a busy 24 hours for mergers and acquisitions bankers, with close to $40 billion worth of deals announced across Sunday and Monday. Marriott raised its offer to buy Starwood Hotels, snatching it back from a huge Chinese insurer, and UK financial data giant Markit is merging with its US rival IHS.

Business Insider had an exclusive interview with Ray Dalio, founder of Bridgewater Associates. He talks about the appointment of a new co-CEO, the firm's unique culture, and why it is misunderstood. It is definitely worth a read.

We also take a look at the topic du jour of bond market liquidity, and why some official sector research is at odds with the view of most Wall Street executives.

And here is a comprehensive summary of the best Wall Street careers advice we've heard.

Here are the top Wall Street headlines at midday:

The next housing crisis is here - This time the crisis is all about one thing: supply.

A wave of bankruptcies from American oil companies won't be enough to trigger a recession - Recessions usually come from a series of dominoes falling.

The world's largest oil driller just gave a very bearish presentation on the future of the industry - The world's largest oil driller is expecting the industry to worsen in the second half of the year.

A lot of people are making the same mistake about Tesla and the Model 3 - Tesla will unveil its much-anticipated Model 3 mass-market vehicle in Los Angeles at the end of March.

ESPN's Darren Rovell thinks he knows how Twitter can make an extra $4.5 billion a year - ESPN Sports Business Reporter Darren Rovell has a plan to help improve Twitter's user experience while also boosting it's bottom line: The introduction of a tiered pricing model.

One of Rolex's most iconic models just got a huge update - It's always news when Rolex drops an update for one of the iconic models in its lineup, and this year is no different.

31 hot cars we can't wait to see at the New York Auto Show - There's going to be plenty of automotive hotness and new everyday models to go around.