What you need to know on Wall Street today

Welcome to Finance Insider, Business Insider's summary of the top stories of the past 24 hours. Sign up here to get the best of Business Insider delivered direct to your inbox.

Wall Street was abuzz this week with Goldman Sachs bankers and rival financiers questioning what was behind the firm's Monday announcement that securities division coheads Pablo Salame and Isabelle Ealet would be leaving the bank in June.

We spoke with more than half a dozen Goldman Sachs partners past and present, as well as close confidants to current partners, to understand what happened and what it means for the firm going forward.

Here's our story: Inside the shakeup at the top of Goldman Sachs' trading division - and what it means about the future of the firm.

In deal news, PayPal is buying the Swedish card-reading startup iZettle for $2.2 billion, and Square should be worried. Ad industry execs are buzzing about a potential sale of LiveRamp, one of the most trusted marketing-data platforms.

And in activist news, hedge fund manager David Tepper now has the go-ahead to go full activist on Allergan if he wants to.