What you need to know on Wall Street today

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Sweeping financial regulatory reforms in Europe - which have been in the works for seven years - finally went live on Wednesday.

The lengthy and complex set changes, known as the Markets in Financial Instruments Directive II (MiFID II), will impact a broad swath of financial firms across the globe, but especially investment banks that do business in Europe. Here's how banks will be affected.

In other news, Spotify has reportedly filed for its IPO in secret. And in markets news:

• Tesla's highly anticipated Model 3 delivery report has traders bracing for the worst
• JEFFERIES: There's an unorthodox way for traders to protect against big stock market losses
• BANK OF AMERICA: Stocks could surge 19% this year because investors are the right kind of cautious
• Blackstone's Byron Wien unveils his big surprises for 2018

Here's what you missed over the holidays:

The world's hottest investment product is showing signs of slowing down - It used to be that if you wanted to attract interest in an exchange-traded fund, all you had to do was launch one. After all, as the ETF market exploded over the past decade, investor demand seemed to outpace supply.

The best stock market trade of 2017 was one that experts hate - The best stock market trade of 2017 doesn't involve a specific stock or sector. It instead relates to price fluctuations in equities - or in this case, the lack thereof.

Traders are betting billions that the hottest stocks of 2017 will get crushed - The so-called FANGS - Facebook, Apple, Netflix, and Google - helped drive the S&P 500 to what's set to be its best year since 2013. But they've also attracted a swarm of short sellers.

We asked the founder of a tech advisory firm with over $1 million in revenue per employee how they sort the real unicorns from the pretenders - The past decade has seen an unprecedented rise in tech entrepreneurship, with $1 billion "unicorns" morphing from a rare creature to a mundane sighting in the process.

An industry insider just blew the lid off the racket that makes American drugs so expensive - The infamous "pharma bro" Martin Shkreli is in jail, but the egregious drug-price-gouging scheme that shocked America and made him a household name last year is still doing just fine.

Theranos is gearing up for a rebound with $100 million to get it through 2018 - Theranos is gearing up for its rebound.

A partner at one of the top bitcoin trading firms told us why crypto is "such an amazingly fun space to be in" - The news that Cboe Global Markets was going to launch a futures market for bitcoin was a landmark moment for trading firm Akuna Capital.