Clear Night Group has purchased Minneapolis brand agency Modern Climate, the fourth acquisition by the St. Paul-based holding company to create what it calls a marketing platform.

Modern Climate’s 26-person firm, which was named by Advertising Age as one of the country’s best small agencies in 2012, will maintain its name and downtown offices, John Hyduke, Clear Night Group president and chief executive, said Wednesday.

The sale is expected to close July 1. Terms were not disclosed.

“Adding Modern Climate to the platform that we have gives us an opportunity to get to scale in Minneapolis,” Hyduke said.

Modern Climate is known for its experiential marketing and technological innovation. It helped 3M Co. develop a digital version of its Post-it notes and Caribou Coffee Co. and Uber Technologies Inc. create an April Fools’ Day promotion with free pedicab rides in the skyway.

Modern Climate President and Chief Creative Officer Keith Wolf said the agency would try to remain innovative and entrepreneurial.

“As those expectations with clients grow … it allows Modern Climate to scale when we need it. For us, it was the best of both worlds,” he said.

Founded in 2009, Modern Climate has gained six new clients since the beginning of the year and grown revenue 15 to 20 percent in the last six months, Wolf said.

Clear Night Group in April bought digital marketing firm Ackmann & Dickenson. In 2014, it bought creative agency Gabriel deGrood Bendt (GdB), and, last year, McFarland Communications joined Clear Night Group and became GdB Pitch, its public relations arm.

Hyduke said Clear Night may acquire another firm in the next year and a half.

Created in 2012, Clear Night Group is a subsidiary of South Carolina media conglomerate Evening Post Industries.