Columbia Pipeline Partners LP (CPPL), the midstream master limited partnership (MLP) backed by one of the nation’s largest utility companies, NiSource Inc., shattered records last week when it sold 46.8 million common units and raised about $1.1 billion in the largest such initial public offering (IPO) in history.

The company upsized its offering from 40 million common units priced at a range of $19-21 each to launch at $23 (see Shale Daily, Jan. 28). In its first day of trading on the New York Stock Exchange, units opened at $28 and finished at $26.79. They were trading near $28 on Monday.

The MLP is part of a broader plan to separate NiSource and its Columbia Pipeline Group into two separately traded public companies (see Shale Daily, Sept. 30, 2014). Under the plan, expected to be complete by the middle of this year, CPG would own nearly all of NiSource’s natural gas transmission, midstream and storage assets, or 15,000 miles of interstate natural gas pipeline, 300 Bcf of natural gas storage capacity and a portfolio stuffed with related growth plans. The MLP would own a 14.6% interest in the assets of CPG and be spun off with the new company.

Last week’s debut came just three months after Antero Resources Corp. set a record with its own midstream MLP IPO (seeShale Daily, Nov. 6, 2014). In November, Antero Midstream Partners LP sold 40 million common units and raised $1 billion, outperforming Royal Dutch Shell plc’s midstream MLP offering by just a few hundred thousand dollars, which had set the previous record just days before (seeDaily GPI, Oct. 29, 2014).

Similar to CPPL’s offering, those deals came at a time when the price of oil was rapidly falling and natural gas was taking a similar plunge. But while the exploration and production and oilfield services sectors have taken a beating on the stock markets in recent months, investors have been drawn to the stability of certain midstream MLPs as the broader U.S. economy gains strength and they have more money to invest, said Hillary Holmes, a partner at Baker Botts LLP, which represented underwriters in the CPPL offering.

“We think this is indicative of two things. One, the MLP market is still very strong for certain types of businesses — those mostly focused on the midstream space — with longer term firm transportation contracts, very predictable cash flow and credit worthy customers; plus the strong sponsor behind them with a long drop-down runway, which Columbia had,” she said.

“If you look at the prospectus, you’ll see the potential for growth projects and I think for a lot of investors that was an easy story to get.”

After the split, NiSource would retain its regulated gas utilities, which serve more than 3.4 million customers in seven states, and continue providing electric distribution, generation and transmission services in northern Indiana. CPG, meanwhile, would take control of the company’s midstream assets and the tax-advantaged MLP would help generate steady cash flows.

Some of CPG’s system is already being upgraded, while a long-term plan to improve its infrastructure and storage network to meet a growing supply of natural gas and higher demand is expected to cost $12-15 billion over the next decade.

Midstream MLPs have raised billions of dollars over the last two years. In 2013, Holmes said 19 midstream MLP IPOs raised $4.7 billion. Last year, 18 such offerings raised $6.7 billion. CPPL’s IPO could also grow to $1.2 billion if underwriters exercise their option to purchase more than seven million additional units.