Data analytics provider ComScore said it would buy viewership rating company Rentrak in an all-stock deal with an implied value of about $771 million to create a comprehensive measurement system for media and ad industries.
The deal could challenge Nielsen NV, the dominant player in television ratings, which are considered the currency used to determine ad rates for commercials.
"This merger also recognizes the critical importance of combining digital and TV assets for next generation media measurement," ComScore's CEO Serge Matta said.
ComScore, one of the biggest players in Web tracking, has shifted increasingly into advertising measurement and is especially strong in so-called display, or banner ad analytics.
Rentrak will merge into a wholly owned subsidiary of ComScore, and each share of Rentrak will be converted into the right to receive 1.15 shares of ComScore.
The offer implies a premium of 9.9 percent to Rentrak's Tuesday close of $43.39.
Rentrak's shares rose 13 percent in extended trading, while ComScore's shares rose 8 percent.
After the deal closes, ComScore shareholders will own about 66.5 percent of the combined company, with Rentrak shareholders holding the rest.
J.P. Morgan Securities advised ComScore and Goldman Sachs advised Rentrak.
The deal is expected to close by early 2016.
ComScore said it expects the deal to slightly hurt its adjusted earnings per share in 2016 and add to earnings in 2017.