Why is Inovio Pharmaceuticals stock plunging today?

Shares of Inovio Pharmaceuticals fell nearly 19.7% in mid-day trading to reach $1.165, after the biotechnology company priced an underwritten public offering of approximately 58.7 million common shares at $1.05 per share, along with pre-funded warrants to purchase an additional 12.7 million shares at $1.049 per warrant, targeting gross proceeds of roughly $75 million before underwriting discounts and commissions. The offering price represented a meaningful discount to the stock’s prior close of $1.45, immediately signaling dilution pressure to existing shareholders.

The scale of the capital raise amplified the negative reaction: underwriters were also granted a 30-day option to purchase up to an additional 10.7 million shares at the offering price, potentially adding further dilution on top of the base deal. Options market activity underscored the bearish sentiment, with put-option volume surging to roughly 33,262 contracts — approximately 722% above typical levels — while overall share volume ran at roughly five times the average daily pace. Jefferies, Piper Sandler, and H.C. Wainwright & Co. are managing the offering, which is expected to close around November 9, 2026. The company is also set to report its third-quarter 2026 financial results on November 10, 2026, adding another near-term uncertainty for investors.

The broader market environment offered little cover for Inovio’s decline. The S&P 500 and Nasdaq were both in recovery mode today, bouncing back after a severe AI-driven tech sell-off the prior session, with the Nasdaq gaining +1.6% and the S&P 500 adding +0.9% — making Inovio’s steep drop entirely a company-specific event rather than a sector-wide or macro-driven move.

Taken together, the deeply discounted offering price, the magnitude of share dilution, the elevated options bearishness, and the looming earnings release created a confluence of selling pressure that overwhelmed any benefit from the broader market’s rebound, pushing Inovio shares to an intraday low of $1.07 against a 52-week high of $2.72.