Vestcor Inc Invests in SIGA Technologies Vestcor Inc has acquired a new stake in SIGA Technologies, purchasing 48,177 shares worth approximately $290,000 in Q4. This adds to growing institutional interest, with 55.4% of the company now owned by such investors. SIGA’s stock opened today at $5.63, reflecting a year-low of $5.16 and high of $12.83.1