50,000 Robinhood Traders Add Rocket Companies On IPO Debut

Rocket Companies Inc RKT may have priced its IPO under initial expectations, but the stock was a big hit with day traders.

The parent company of Quicken Loans, the nation's largest home mortgage lender, took off Thursday to close the session up 19.5% at $21.51 per share.

Rocket Companies priced its 100-million share IPO offering at $18, under the initial target of selling 150 million shares at an offering price range of between $20 and $22.

Related Link: Dan Gilbert, Jay Farner On Rocket Companies IPO: 'Great Starting Point'

The Robinhood community may have been to thank for the debut surge, as 54,332 accounts bought the stock, according to Robintrack.

Rocket Companies was the most bought stock on the app today, nearly five times as much as the second-most bought stock of the day, Apple Inc. AAPL.

"The investor base for our opening was probably the most important thing," CEO Jay Farner said earlier in the day. "So we focused on that versus selling as many shares as we possibly could."

Robinhood, the popular trading app among millennials, helped usher in the commission-free trading trend.