What you need to know on Wall Street right now

Welcome to Finance Insider, Business Insider's summary of the top stories of the past 24 hours.

Bill Ackman has officially quit Valeant Pharmaceuticals.

The founder of the hedge fund Pershing Square on Monday sold his investment in the company and announced his plan to step down from the board. Valeant's stock is getting hammered.

Ackman pinpointed the moment he should've sold out of Valeant - and he's wrong, according to Business Insider's Linette Lopez. You can follow Valeant's collapse - from Hillary Clinton's tweet to Ackman's exit - right here.

More than 5,000 flights were canceled Thursday as a winter storm slammed the Northeast. Here's how to get the most money back if your flight gets canceled. Natural gas plunged as the blizzard missed NYC.

In deal news, Hudson's Bay is reportedly in talks to buy Neiman Marcus, $13 billion tech titan Citrix is reportedly looking for a buyer again, and $1.2 billion security startup Okta filed for its long-awaited IPO.

In finance news, Deutsche Bank has a new US chief. Wall Street's most important business is having a bumper start to the year. And the war of words between the New York Stock Exchange and IEX, America's newest stock exchange, just took a strange turn.

Futures traders are fully convinced that the Federal Reserve will raise interest rates at its March 14-15 meeting. And it's time to start paying attention to one of the Fed's most controversial charts.

Trump's latest trade target is potentially the most dangerous one, according to Business Insider's Pedro da Costa.

There's a bunch of news around the American Health Care Act, the GOP's Obamacare replacement. Here's the latest:

• The CBO says as many as 24 million more Americans could be uninsured under "Trumpcare"
• The GOP's Obamacare replacement is going to disproportionately affect one group
• Here are the biggest winners and losers from "Trumpcare"
• "We disagree strenuously": Trump team attack CBO's unflattering "Trumpcare" report
• KRUGMAN: "Trumpcare" is "stupid and cruel"
• PAUL RYAN: The CBO report "actually exceeded my expectations"
• A top Republican senator blew up Trump's "3-phase plan" for healthcare overhaul

In tech, estimates for Snap's ad revenue have been cut, and shares just hit a post-debut low. Ford has invested millions in startups to recruit talent - and it has no plans of slowing down.

And in aerospace, Boeing's newest plane is also its biggest headache.

Lastly, here's what to wear when it's freezing and style truly doesn't matter.

Here are the top Wall Street headlines from the past 24 hours.

ROBERT SHILLER: "This market is way overpriced" - Even Robert Shiller is worried about stock market valuations.

The dollar is starting to act like an oil currency - The relationship between the US dollar and crude oil has changed again, reflecting America's growing role in the global oil industry.

Euronet just offered $1 billion to buy MoneyGram, outbidding Alibaba's e-payment company - US electronics payments processor Euronet Worldwide offered to buy US money-transfer company MoneyGram International for more than $1 billion.

Allergan just got exclusive access to a treatment that could revolutionize how we treat genetic diseases - Allergan said on Tuesday it would get exclusive access and the option to license up to five of Editas Medicine's experimental gene-editing-based eye treatments under a research and development deal between the two companies.

CREDIT SUISSE: Here are 5 reasons to like Nike - It's time to like shares of Nike, according to Credit Suisse analysts Christian Buss and others.

The "Bill Gates of China" just splurged on a $41.5 million mansion in New York City - A Chinese billionaire serving 14 years in prison for bribery and insider trading is the new owner of a $41.5 million Upper East Side mansion that sold earlier this week.