ONEOK Inc. struck a deal to acquire all of ONEOK Partners LP's outstanding common units it does not already own for $9.3 billion in ONEOK common stock.

Under the deal, each of the 171.5 million outstanding ONEOK Partners units will be converted into 0.985 share of ONEOK stock, representing a 22.4% premium to the ONEOK Partners closing price Jan. 27. In total, ONEOK will issue 168.9 million shares, representing about 44.5% of the total outstanding of the pro forma combined entity.

"Through the acquisition of the 60 percent of the limited partner interests in ONEOK Partners that ONEOK does not already own, ONEOK becomes a standalone operating company with a lower cost of funding and stronger cash flow generation," said Terry Spencer, who serves as president and CEO of both companies. "We also anticipate the transaction will provide ONEOK enhanced access to the broader capital markets to support and fund future growth to meet the needs of our customers."

ONEOK expects to operate as a diversified midstream provider with a more than $30 billion enterprise value upon the anticipated closure of the deal in the second quarter of 2017. The combined entity will have an integrated 37,000-mile network of NGLs and natural gas pipelines, processing plants, fractionators and storage facilities in the Williston Basin, Mid-Continent, Permian Basin, Midwest and Gulf Coast.

Following deal completion, the company expects that its annual distributable cash flow will approximately double and that it will not pay cash income taxes through at least 2021. The company plans to recommend to the board a 21% increase in the first quarterly dividend and expects to have a 9% to 11% annual dividend growth rate through 2021.

Further, the combined entity is anticipated to receive investment-grade credit ratings. ONEOK is rated at Ba+ by Moody's and BB+ by S&P Global Ratings, while ONEOK Partners is rated at Baa2 by Moody's and BBB by S&P.

The completion of the transaction is subject to the satisfaction of customary conditions, including receipt of requisite approvals of ONEOK shareholders and ONEOK Partners unit holders.

ONEOK tapped J.P. Morgan Securities LLC as lead financial adviser, Morgan Stanley & Co. LLC as financial adviser and Skadden Arps Slate Meagher & Flom LLP as legal adviser on the transaction. ONEOK Partners' conflicts committee engaged Barclays as financial adviser and Andrews Kurth Kenyon LLP as legal adviser.

S&P Global Ratings and S&P Global Market Intelligence are owned by S&P Global Inc.