UPDATE 1-SandRidge Energy's trust unit sees IPO priced at $19-$21/shr

* Trust to offer 26 mln shares

* Adds 9 underwriters to the offering

April 5 (Reuters) - SandRidge Energy's trust unit, SandRidge Mississippian Trust II, expects its initial public offering of 26 million shares to be priced between $19 and $21 apiece.

The trust, formed to own royalty interest in oil and natural gas wells, also added nine underwriters to the offering including BofA Merrill Lynch, Citigroup and RBC Capital.

At the mid-point of its offering price, the trust expects to receive net proceeds of $483.7 million, which it will deliver to one or more of SandRidge's units as consideration for royalties.

In January company had filed with the U.S. regulators to raise up $603.75 million in an initial public offering and applied to list its common stock on the New York Stock Exchange under the symbol "SDR."