Operator
Good day, and thank you for standing by, and welcome to the Rocket Companies, Inc. first-quarter 2021 earnings call. [Operator instructions] I would now like to hand the conference over to your speaker today, Sharon Ng. Please go ahead.
Sharon Ng
Vice President of Investor Relations
Good afternoon, everyone, and thank you for joining us for Rocket Companies earnings conference call covering the first quarter of 2021. I m Sharon Ng, the new vice president of investor relations here at Rocket Companies. With us this afternoon are our CEO, Jay Farner; CFO Julie Booth; and President and COO Bob Walters. Before I turn things over to Jay, let me quickly go over our disclaimers.
During the fourth quarter of 2020, Rocket Companies:
Grew total revenue, net, for Rocket Companies to $4.7 billion from $1.9 billion in Q4 2019 and Adjusted Revenue to $4.8 billion from $1.8 billion in Q4 2019.
Grew net income to $2.8 billion from $0.8 billion in Q4 2019 and Adjusted Net Income to $2.3 billion from $0.5 billion in Q4 2019.
Generated record closed loan origination volume of $107.2 billion and net rate lock volume of $96.0 billion in the fourth quarter of 2020, which represented improvements of 111% and 119%, respectively, as compared to the fourth quarter of 2019.
Increased gain on sale margin by 100 basis points year-over-year to 4.41%.
Rocket Auto, our automotive retail marketplace, facilitated the sale of 9,400 auto units, up more than 2,000 units as compared to fourth quarter of 2019.