In a new round of funding, Zenefits, an HR company focused on integrating health insurance, payroll, and 401k services, succeeded in raising $500 million, raising the startup to a $4.5 billion valuation.

Amongst the investors are: actor Ashton Kutcher (That 70’s show star), and venture capitalist Marc Andreessen (who was also an early investor in Twitter and Facebook).

Zenefits CEO Parker Conrad had this to say: “If you think about it like we’re driving a car, we want to go extremely fast at an extremely high speed, and go very far. And if you want to do that you’re gonna burn a lot of gasoline. So this round we had to do the mother of all pit stops for gas and beef jerky, to continue building at the speed that we’re going.”

Ashton Kutcher has been building a name for himself in Silicon Valley. Within the past couple of years, he also bought into Foursquare, and Skype (before it was acquired by Microsoft). What’s he doing with all the money he’s making from his big bets? Well, for one thing, he recently renovated his childhood home to pleasantly surprise his mom.

“It’s my way of saying ‘thank you’ to my mom,” reported Kutcher. “She has been the greatest influence in my life.”