Shares of Zymeworks Inc. /zigman2/quotes/208104417/composite ZYME -0.32% rallied 1.5% in morning trading Friday, after the biopharmaceutical company said it rejected the "unsolicited, opportunistic, non-binding" $10.50-per-share buyout bid by activist investor All Blue Falcons FZE. The company said it determined that the bid by the UAE-based investment holding company "significantly undervalues" the company and its prospects, and "lacks credibility" by offering no information regarding funding. The stock had soared 23.2% on April 29, three days after closing at a record low, after the company confirmed it had received the bid from All Blue Falcons for $10.50 in cash. The stock had rallied to a post-bid high of $7.15 on May 3, which was 31.9% below the bid price, before pulling back. The stock was recently trading 43.7% below the bid price. The stock has plunged 63.9% year to date, while the iShares Biotechnology ETF /zigman2/quotes/206189322/composite IBB +1.72% has dropped 24.3% and the S&P 500 /zigman2/quotes/210599714/realtime SPX +3.06% has lost 17.5%.