After years of delay, former stockholders of Massey Energy Co. have lost standing to bring a derivative suit against company executives over a 2010 mine explosion that killed 29 workers, the Delaware Court of Chancery said on Thursday.

In a 49-page opinion, Chancellor Andre G. Bouchard said the claims of two pension funds, which formerly held stock in Massey, were extinguished when the company was purchased in the wake of the disaster.

The shareholders, two pension funds, filed their lawsuit in April 2010, just weeks after a piece of coal-mining equipment set off a massive fireball that ripped through two-and-a-half miles of a mine, killing all but two of the men working at Massey's Upper Big Branch mine in West Virginia.