** Hallador Energy's HNRG.O shares down 21.7% premarket to $14.75 after disclosing its conversion transaction commitment agreement being terminated by the counterparty

** Terre Haute, Indiana-based electricity and coal producer said it learned at the close of business on May 19 that agreement with a leading global datacenter developer was being terminated, according to the SEC filing late Thurs

** The counterparty to the agreement, which was effective Jan 2, was not named

** As discussed on May 12 earnings call, the parties continue to discuss an additional exclusivity period and continue in non-exclusive talks, co said in the filing

** Co said it's evaluating opportunities with several other interested third parties

** Through Thurs close, HNRG shares up ~64 YTD, including ~34% surge this month. Stock hit record intraday high of $19.71 on Weds

(Lance Tupper is a Reuters market analyst. The views expressed are his own)

((lance.tupper@tr.com 1-646-279-6380))