SandRidge Permian Trust (PER) started trading on the NYSE

The shares of SandRidge Permian Trust (PER), an oil and gas royalty trust, were unchanged in their stock market debut after tumultuous markets curtailed most initial public offerings scheduled for this week.

• $540 million by selling 30 million units for $18 each -- less than the 31.5 million units it planned to sell for $19 to $21 each

The IPO raised $540 million -- 14 percent less than anticipated -- but still got done, reinforcing the idea that investors are strongly interested in yield.

SandRidge Permian Trust is promising investors a cut of its proceeds from selling oil, natural gas and natural gas liquids.

On Wednesday, the trust raised $540 million by selling 30 million units for $18 each -- less than the 31.5 million units it planned to sell for $19 to $21 each. The shares ended at $18 on Thursday on the New York Stock Exchange.

SandRidge has 509 producing wells, including 13 that are not complete, and plans to drill another 888 development wells. The wells are in the Permian Basin in western Texas.

As natural gas prices remain low and drilling costs remain high, smaller oil and gas producers are searching out new sources of funding. Joint ventures and asset sales are one option; IPOs are another.

In April, SandRidge did an similar IPO of wells in Oklahoma that were listed as SandRidge Mississippian Trust I (SDT). Common units of that trust closed at $24.48, or 16.6 percent above their $21 IPO price.

Underwriters on the SandRidge IPO were led by Morgan Stanley, Raymond James, RBC Capital Markets and Wells Fargo Securities.