 SANTA FE, NM ACCESSWIRE June 28, 2021 Sigma Labs, Inc. NASDAQ:SGLB Sigma Labs, a leading developer of quality assurance software for the commercial 3D metal printing industry, has been added to the Russell Microcap Index effective at the open of trading today, marking the annual Russell U.S. Indexes reconstitution. Membership in the Russell Microcap Index means automatic inclusion in the appropriate growth and value style indexes. 