May 6 (Reuters) - Infrastructure investment firm I

Squared, midstream company MPLX LP ( MPLX ), and pipeline

operator Enbridge Inc ( ENB ) have entered an agreement to

acquire up to 85% interest in the Matterhorn Express gas

pipeline, the companies said on Tuesday.

Infrastructure company WhiteWater, which counts I Squared as

one of its partners, will own up to 65% interest in the

pipeline, the companies said in a statement, adding that

Canada-based Enbridge ( ENB ) and MPLX ( MPLX ) will own another 10% each in the

Matterhorn pipeline following a closing of the transaction.

The companies would acquire these equity interests from

private equity firm Ridgemont Equity Partners and Devon Energy

Corp ( DVN ), the statement said.

Reuters reported earlier this week that Miami-based I

Squared Capital was in talks to acquire a majority stake in the

natural gas pipeline from WhiteWater Midstream. A deal could

value Matterhorn Express pipeline at more than $5 billion

including debt, a Bloomberg report had said.

WhiteWater's equity interest in the Matterhorn Express

Pipeline will be jointly backed by infrastructure investment

firm FIC and I Squared, according to the statement. WhiteWater

will continue to operate the Matterhorn Express Pipeline.

Earlier on Tuesday, MPLX ( MPLX ) said it is acquiring an additional

5% interest in the joint venture that owns the Matterhorn

Express pipeline for $151 million.

The Matterhorn pipeline carries natural gas from the Permian

Basin of West Texas and New Mexico to the outskirts of Houston.

The 580-mile pipeline was designed to carry up to 2.5 billion

cubic feet per day of gas, according to its website.