HOUSTON/HONG KONG—A Chinese investment firm is attempting to restructure an $812 million deal for the U.S. developer of the Alerian MLP Index .AMZ, which tracks publicly traded energy infrastructure companies, three people familiar with the matter said in recent days, after missing two deadlines to close the deal.

Hong Kong-based ZZ Capital International Ltd. agreed last July to buy Alerian, a Dallas-based financial index and data provider, for $582 million in cash and up to $230 million in additional payments if it hit revenue targets from 2018 to 2021.

ZZ Capital declined to comment. Alerian did not respond to requests for comment on April 10 and earlier declined to make its chief executive available for comment on the status of the agreement.

A collapse of the deal would demonstrate the difficulties Chinese companies now face in financing and purchasing high-profile U.S. assets. Chinese regulators last year began pressuring domestic banks to rein in their overseas investments, reducing capital for deals.

That clampdown has required ZZ Capital to seek “offshore funding for existing deal pipeline” and slow new M&A proposals, it said in a regulatory filing in February.

While small, Alerian has a significant role in promoting infrastructure investments, especially in U.S. shale fields, through its indexes and data on energy investments.

Both parties were continuing to negotiate the deal, the sources familiar with the matter said this week.

The purchase originally was expected to close by December, but ZZ Capital said in January it had won an extension to March 31 to fulfill undisclosed conditions. It has not publicly commented since last month’s deadline expired.

The U.S. Committee on Foreign Investment in the United States, an intra-government agency that scrutinizes foreign groups’ purchases of U.S. assets to protect national security interests, rejected the initial application for the Alerian deal, one of the sources said on April 11.

A Treasury Department spokesman for CFIUS declined to comment, noting the agency is prohibited from disclosing information filed with it.

Alerian is majority-owned by Gabriel and Daniel Hammond, brothers who also own Broad Green Pictures, a Los Angeles film and television production venture. Gabriel Hammond did not respond to an emailed request for comment.

Alerian’s indexes track energy MLPs and provide financial data on energy infrastructure projects in the United States. Terms of the deal included a $25 million breakup fee to Alerian if the transaction was not concluded by March 31.

MLP investments have been hard-hit, first by the 2014 downturn in crude prices and more recently by regulatory and taxation shifts. The Alerian MLP Index is down 13% this year and major MLPs are restructuring from limited partnerships to traditional corporations.

ZZ Capital also has had a number of executive departures, including from its overseas investment department and international deal execution team, one of the sources said last week.

In February, ZZ Capital disclosed its CEO resigned and also released unaudited results for the nine months ended Dec. 31 showing its after-tax profit had slipped to $10.3 million from $12.15 million a year earlier.

The company told Hong Kong regulators at the time that it would “pursue cost cutting as well as short-term income opportunities” in the quarter ending March 31.