This mission began in 1998 when our founder and Chairman, Dan Gilbert, wrote an email committing all of the company's resources to moving online.
We've continued to strengthen our digital products and infrastructure in 2020, deploying nearly 4,500 product features throughout the year and delivering improvements to our platform every 28 minutes on average.
I'm pretty sure the majority of you were among the nearly 100 million fans who watched the Super Bowl a couple of weeks ago.
1 and 2 on USA Today's ad meter, which I am certain is the most prestigious consumer ranking of top Super Bowl ads.
All told, our Super Bowl activation resulted in more than 3.3 billion consumer impressions.
Another pillar of our business model is the incredible Rocket Cloud Force, now consisting of more than 6,600 U.S.-based professionals trained to advise our clients on complex transactions.
In fact, since the beginning of 2019, data science has driven more than $75 billion in application volume.
It took our company 25 years to close our first 1 million loans.
In 2020 alone, we have helped more than 1.1 million clients with their mortgage, automotive, real estate, or personal loan needs.
Starting from zero in 2017, we've organically scaled Rocket Auto to more than $750 million of gross merchandise value in 2020.
Partner volume made up 38% of our closed loan volume in 2020, up from 23% just two years ago.
All of our businesses performed above expectations, leading to a full-year adjusted revenue of $16.9 billion and adjusted EBITDA of $11.1 billion.
As Julie will soon explain, our Board has authorized a special dividend of $1.11 per share for holders of our stock as of March 9 to be paid on March 23.
Julie and I have worked together inside this company for 17 years.
For the full-year of 2020, Rocket Companies generated $16.9 billion of adjusted revenue and $11.1 billion of adjusted EBITDA as we wrapped up a record-setting year.
For the full-year 2020, we generated $320 billion of closed loan volume, representing an increase of 121% year over year.
2020 was also a year of robust growth across Rocket Companies, with particular strength at Amrock, our title company, with revenues increasing 124% to $1.3 billion during the year.
Rocket Auto, our automotive retail marketplace, also generated robust results orchestrating more than $750 million in gross merchandise value of automotive e-commerce transactions.
This equates to just over 32,000 auto units in 2020 up more than 60% as compared to 2019.
We finished 2020 on a particularly strong note, with fourth-quarter rate lock volume of $96 billion and closed loan volume of $107 billion, both significantly exceeding the high end of our expectations.
Rocket Homes also finished the year on a strong note as they assisted clients with nearly $1.6 billion of real estate transactions during the fourth quarter alone.
Our full-year closed volume growth of 121% substantially exceeded any estimate of the overall industry's growth from third-party sources, which estimates 67% growth on average.
To put this in perspective, Rocket Mortgage's incremental closed volume of $175 billion in 2020 and was more than double the growth of any other market participant.
For the full-year 2020, a Rocket's adjusted revenue increased by $11 billion year over year.
We drove this revenue growth while only adding $2 billion of expenses during the year, or $3 billion of annualized operating expenses based on our fourth quarter.
As an example, our data science team now includes over 300 professionals.
We are very impressed with our initial pilot where we are seeing 20% improvement in turn times within the pilot group.
In two years, our partner network has grown from less than $20 billion in closed loan volume to $120 billion on an annual basis.
We expect closed loan volume of $98 billion to $103 billion compared to $51.7 billion in the first quarter of 2020; net rate lock volume of $88 billion to $95 billion, up from $56 billion in the first quarter of 2020; and gain-on-sale margins of 3.6% to 3.9% compared to 3.25% in the first quarter of 2020.
We ended 2020 with an extremely strong balance sheet, including $2 billion of cash and $7.7 billion of total liquidity.
Given our record level of profitability in 2020, the Board approved a special dividend of $1.11 per Class A common share funded by an equity distribution of $2.2 billion.
Additionally, we remain authorized to repurchase up to $1 billion of Rocket Companies' common stock.

Summary:
As Julie will soon explain, our Board has authorized a special dividend of $1.11 per share for holders of our stock as of March 9 to be paid on March 23.
We expect closed loan volume of $98 billion to $103 billion compared to $51.7 billion in the first quarter of 2020; net rate lock volume of $88 billion to $95 billion, up from $56 billion in the first quarter of 2020; and gain-on-sale margins of 3.6% to 3.9% compared to 3.25% in the first quarter of 2020.
Given our record level of profitability in 2020, the Board approved a special dividend of $1.11 per Class A common share funded by an equity distribution of $2.2 billion.