Three leading Am Law 100 firms are advising on a $2.6 billion all-stock deal that will see electric carmaker Tesla Motors Inc. acquire solar energy company SolarCity Corp.

Elon Musk, the billionaire technology investor who frowns upon patents, owns more than 20 percent of both companies. Tesla and SolarCity will now combine their operations to create what both entities claim will be the world’s only vertically integrated sustainable energy company.