WillScot has made an offer for Mobile Mini that values it in the mid-to-high $30-per-share range, which would be funded for the most part by using WillScot shares as currency, sources told Reuters on Wednesday.

Mobile Mini shares were trading up 5% at $36.42 before news of Elliott's involvement, giving the company a market value of $1.6 billion. WillScot shares were up 4% at $16.23, giving it a market value of $1.9 billion.

Elliott, which has pursued changes at some of the biggest U.S. companies, including AT&T Inc and eBay Inc , believes that a combination with WillScot is the best transaction available to Mobile Mini, the sources said.

Reuters reported on Wednesday that Mobile Mini is also considering alternative transactions, including acquiring the U.S. assets of mobile storage company General Finance Corp, should the latter divest its Australian portable buildings and storage container business Royal Wolf Holdings.

There is no certainty that WillScot will successfully negotiate a deal with Mobile Mini, the sources said, asking not to be identified because the matter is confidential. The sources did not give details on the size of Elliott's stake in Mobile Mini.

Elliott, Mobile Mini and WillScot declined to comment.

Headquartered in Baltimore, Maryland, WillScot has a fleet of approximately 160,000 modular space and portable storage units. Private equity firm TDR Capital LLP is a major investor.

Mobile Mini, based in Phoenix, Arizona, has a rental fleet of about 198,000 storage containers and office units, as well 12,700 liquid and solid containment units and pumps that it also rents out.

Besides Elliott, The Donerail Group, an investment firm led by former activist hedge fund Starboard Value LP executive William Wyatt, has built a stake in Mobile Mini to push it to explore a sale, Reuters reported earlier this month.

Beyond Royal Wolf, General Finance owns Lone Star Tank Rental Inc and Pac-Van, providers of portable storage, office and liquid storage tank containers, mobile offices and modular buildings. It is based in Pasadena, California, and has a market capitalization of $280 million.

(Reporting by Greg Roumeliotis, Editing by Rosalba O'Brien)

By Greg Roumeliotis