NEW YORK — Investment bank Morgan Stanley announced it would buy the online brokerage company E-Trade for roughly $13 billion, one of the biggest deals on Wall Street since the Financial Crisis.

The deal also is the latest chapter in Morgan Stanley's transformation from the scrappy investment bank to a more well-rounded financial firm now more reliant on its asset and wealth management businesses.

Under the terms of the deal, E-Trade shareholders will receive 1.0432 shares of Morgan Stanley for each share they own.