Shares of Voyager Therapeutics Inc. /zigman2/quotes/205091781/composite VYGR +3.33% rocketed 38.9% in premarket trading Wednesday, after closing at a record low in the previous session, after the gene therapy company announced a license option agreement with Pfizer Inc. /zigman2/quotes/202877789/composite PFE -0.62% that could valued at more than $600 million. Trading volume spiked up to 3.9 million shares ahead of the open, which compares with the full-day average of about 173,000 shares. The agreement allows Pfizer to exercise options to license novel capsids generated from Voyager's RNA-driven screener technology, which would be used by Pfizer to develop, make and commercialize gene therapies. As part of the agreement, Voyager will receive an upfront payment of $30 million, and is entitled to receive up to $20 million in exercise fees. Voyager will also be eligible to receive up to $580 million in milestone payments, and will be eligible to receive "mid- to high-single-digit tiered royalties" based on sales of Pfizer products using the licensed capsids. The stock, which closed at a record low of $2.47 on Tuesday, has tumbled 36.5% over the past three months while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.31% has inched up 0.1%.