ClearSign Technologies Corporation set to join Russell Microcap® Index

SEATTLE, June 7, 2021 /PRNewswire/ --ClearSign Technologies Corporation (Nasdaq: CLIR) ("ClearSign" or the "Company"),is set to join the Russell MicrocapIndex at the conclusion of the 2021 Russell indexes annual reconstitution, effective after the US market opens on June 28, according to a preliminary list of additions posted June 4.