MICROSOFT BUYS LINKEDIN: What you need to know on Wall Street right now

Tony Chung, LinkedIn

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There's a lot going on in the tech industry today. Here are the top headlines:

• Microsoft is buying LinkedIn for $26.2 billion.
• Microsoft chief Satya Nadella and LinkedIn CEO Jeff Weiner talked to Business Insider about the deal - here's what they said.
• Here's what Nadella told Microsoft employees about the deal.
• Here's what Wall Street thinks about the deal.
• Allen & Co., one of Wall Street's most secretive firms, advised LinkedIn on the deal.
• Three banks could reap as much as $65 million in fees from the deal.
• Twitter shares spiked after the Microsoft-LinkedIn deal was announced.
• Microsoft buying LinkedIn is good for Pandora.
• Symantec is buying Blue Coat Systems for about $4.65 billion.
• Here are the tech companies most likely to be acquired next.
• Short seller Andrew Left is going after Facebook.

In other news, Theranos got ditched by its biggest partner - here's what it has left.

The company that sells wedding rings to much of America is in big trouble. Chipotle still hasn't answered one question about the business - and it could mean doom for the company.

And an upstart trading venue is trying to eat everyone else's lunch.

Here are the top Wall Street headlines at midday:

Gun stocks are surging - Shares of major gunmakers rallied in trading on Monday, one day after the deadliest mass shootingin US history.

This is the biggest risk facing the planet - A Bank of America Merrill Lynch team led by Beijia Ma said in a report to clients that water is the number one pressing issue for the world as whole.

We're witnessing 'the death of investment' - Generally, the best method of saving for retirement is thought to be a diversified portfolio consisting of both stocks and bonds held for a long period of time. This decreases risk while allowing for a long-term accumulation of wealth.

The investment world has a new 'haute couture' - "The 'House of Quant' has firmly established itself as the hedge fund industry's most fashionable strategy due to its high quality product," Credit Suisse said in a recent note to investor clients.

The housing market is trapped - Long-term and short-term trends have converged, and while it hasn't caused disaster for American homeowners yet, it certainly has made movement a lot harder.

MORGAN STANLEY: Pretty soon there's going to be too much oil again - It's been quite a year for oil.

'Hopefully we won't be Banky McBankface': Startup bank Mondo is letting customers change its name - Hot startup bank Mondo is having to change its name following a trademark dispute and is letting its customers chose what it should now be called.