Rattler Midstream LP, a subsidiary of Permian Basin pure-play Diamondback Energy Inc., began trading on Nasdaq Thursday via a better-than-expected public offering.

The initial public offering (IPO) was increased to 38 million common units priced at $17.50 each, representing about 4.6 million more than the original proposal. Rattle also granted the underwriters a 30-day option to purchase up to 5.7 million more common units at the IPO price.

The common units are trading on the Nasdaq Global Select Market under the ticker symbol "RTLR." As of midday Thursday, Rattler had gained about 2% to $17.86.

The common units represent about 25% limited partner interest in Rattler, with Midland, TX-based Diamondback owning 75%. Net proceeds estimated at $631.8 million were to be distributed to Diamondback.

Rattler was formed last summer to own, operate, develop and acquire infrastructure in the Midland and Delaware sub-basins of the Permian. It provides services under long-term, fixed-fee contracts.

In late 2018, Rattler exercised an option to acquire a 10% equity interest in Phillips 66 Partners LP's Gray Oak crude pipeline system, and it increased its volume commitments. Gray Oak is being designed to transport up to 900,000 b/d from the Permian and Eagle Ford Shale to the Texas coast.

Credit Suisse, BofA Merrill Lynch, J.P. Morgan acted as lead book-running managers for the Rattler IPO, and Barclays, Citigroup, Goldman Sachs & Co. LLC and Wells Fargo Securities acted as joint book-running managers.

Renaissance Capital, which tracks IPOs, indicated Rattler’s is the largest U.S. energy offering to date this year.

Austin, TX-based Brigham Minerals Inc. launched an IPO in mid-April to bring in about $100 million, which it achieved. It was trading on Thursday above $21/share with a market cap above $1 billion. Brigham has an existing portfolio of about 40,000 net acres and an estimated 11,648 undeveloped horizontal drilling locations, with mineral and royalty stakes in the Anadarko, Denver-Julesburg, Permian and Williston basins.