I assume you mean Rockville, not Rockwell.
Per the prospectus in Feb., Rockville held 218,750 shares or 6.94% of the 3,153,789 issued and outstanding shares.
Per the 10-K, there are now 4,570,199 issued and outstanding shares. So Rockville now only owns 4.8%, which is less than the 5% threshold that Sigma uses in reporting beneficial ownership. Rockville is no longer a beneficial holder that needs to report their holdings.