Billionaire Kelcy Warren’s attempt to buy Targa Resources Corp. (NYSE: TRGP) in what would have been the year’s biggest energy deal broke down on June 19, Bloomberg said on June 20. Targa shares slipped the most in more than two years.

Energy Transfer Equity LP (NYSE: ETE), Warren’s pipeline conglomerate, was aiming for a deal that would value Targa and operating unit Targa Resources Partners LP (NYSE: NGLS) at more than $15 billion, two people with knowledge of the matter said. After the talks became public, Targa issued a statement late June 19 saying “high level” negotiations were terminated without an agreement.

“There are no assurances whether or not discussions could resume or whether any agreement could be entered into in the future,” said Targa, one of the leading exporters of natural gas products in the U.S.

The purchase would be the largest ever orchestrated by Warren, who expanded Dallas-based Energy Transfer, through a $13 billion buying spree in 2010 and 2011, into the country’s fourth-biggest pipeline company, according to data compiled by Bloomberg. The U.S. shale fracking boom is increasing fuel supplies and propelling deals among the companies that transport oil and natural gas.

Targa Resources Corp. and Targa Resources Partners, both based in Houston, plunged, giving back gains made after Bloomberg News reported the deal talks June 19. Targa Resources Corp. declined 8.7% to $137.59 at 9:52 a.m. in New York, the most intraday since August 2011. Targa Resources Partners declined 12%, after an 18% rise. Energy Transfer rose 0.7%.

Targa said talks with Energy Transfer and “certain of its affiliates” were called off, in a statement released three hours after the potential deal was first reported. The talks were active as of earlier in the day, said a person with knowledge of the matter. The deal could have valued Targa’s assets as high as $17 billion, one person said.

“The midstream is where the money is right now,” said Bernard Weinstein, associate director of Southern Methodist University’s Maguire Energy Institute, in a telephone interview. “That’s why we’re seeing a lot of acquisition activity.”

Negotiations may also have involved Regency Energy Partners LP (NYSE: RGP), another publicly traded pipeline company controlled by Energy Transfer, two of the people said earlier, asking not to be identified discussing private information. Energy Transfer was considering paying for the deal in both cash and stock, one person said.

Representatives for Energy Transfer and Regency didn’t respond to requests for comment.

Energy Transfer is organized as an MLP, which pays no federal income taxes as long as it doles out most of its cash to shareholders. The structure encourages the partnerships to make acquisitions to appease growth-hungry investors who expect increasingly larger dividends.

In another pipeline transaction announced this week, Williams Companies Inc. (NYSE: WMB) agreed to pay $6 billion for control of Access Midstream Partners LP (NYSE: ACMP), with plans to eventually merge the company with its subsidiary Williams Partners LP (NYSE: WPZ).

Energy Transfer and a group of affiliated MLPs own 56,000 miles of gas and crude oil pipelines, along with Sunoco’s 5,000 service stations. In Targa, it would gain a leading shipper of natural gas and associated products such as propane, a business growing as the boom in shale drilling increases fuel supplies.

Targa runs a major processing plant in Mont Belvieu, Texas, and the company owns one of the Gulf Coast’s two commercial export terminals for NGL, according to its website.

Warren, 58, predicted dealmaking would ramp up among infrastructure companies in an interview last September, as railroads and pipeline operators compete for market share, and smaller shippers struggle to keep up. To survive, he said, companies will need geographically diverse operations across an array of products that can withstand slowdowns in individual areas.

Targa Resources Corp. is the general partner of Targa Resources LP, which means it oversees its operations and is entitled to a portion of the cash it distributes every quarter, according to regulatory filings. Targa Resources Corp. had a market value of more than $6 billion after the June 20 gains, while Targa Resources Partners’ market value reached $9.5 billion.

Assuming a value of at least $15 billion, the purchase would be the biggest North American pipeline deal since Houston-based Kinder Morgan Inc. (NYSE: KMI) bought El Paso Pipeline Partners LP (NYSE: EPB) for $21.1 billion in 2012.

Energy Transfer agreed in April to pay $1.8 billion for Susser Holdings Corp. (NYSE: SUSS) and its chain of service stations, which will be merged into Sunoco Logistics Partners LP, one of four primary pipeline partnerships Energy Transfer controls.