The McLean-based media software company Clearspring has secured $20 million from a Silicon Valley investor and plans to use the money for acquisitions and other strategic moves as it looks to broaden its product portfolio, executives said.

This is the fourth round of funding for Clearspring, which has raised $60 million since Chief Executive Hooman Radfar founded the firm in 2004. The company has expanded its Web presence and redefined its core business in that time.

More than 9 million Web sites now tap into Clearspring’s AddThis platform, which allows visitors to share articles, videos and other content across their social networks. In doing so, the company has accumulated reams of data about what content is viewed, shared and clicked on by others.

Clearspring has used that data to build a fast-growing advertising business during the past year that connects major brands to millions of Internet users in real time based on their online behavior.

Radfar said the company plans to use the funds to hire staff, refine its current products and attract new customers. He added that the investment means the company can look more seriously at acquiring small firms that complement its growth goals.

“While we were focused on organically investing at an incremental level with our previous cash . . . we’re now able to look at the world in a different way,” Radfar said. “It’s not just build, it’s buy.”

“A lot of companies are growing quickly and going public by smartly putting together a bunch of smaller companies,” he added.

A slew of local financiers have been part of past funding rounds, including technology executive and Washington sports owner Ted Leonsis, who chairs Clearspring’s board of directors. Steve Case, the former chairman of AOL, is also an investor, along with investment firms such as New Enterprise Associates and Novak Biddle Venture Partners.

Institutional Venture Partners is unique in that it is Clearspring’s first institutional backer from tech-centric Silicon Valley. The firm’s portfolio includes a list of high-profile firms such as Twitter, Netflix, travel search engine Kayak and social media game maker Zynga.

“We’re pretty excited about the round and the partnership, because these guys really get how to take companies to the next level, and we think we have a huge opportunity in terms of the assets we’ve built,” Radfar said.