Why did Moderna stock fall today? Investors come to grips with waning COVID-19 sales
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Moderna (NASDAQ:MRNA) stock slumped more than 6% on Tuesday and posted a five-day losing streak. At their session low, shares hit their lowest level since November 2020. 
The decline has come amid investor concerns about the hit to revenue that COVID-19 vaccine makers face due to waning coronavirus cases and deaths. 
Moderna (MRNA) on Monday reaffirmed its full year 2023 COVID-19 vaccine revenue guidance of $6B to $8B, but also warned that there remained "uncertainty" regarding U.S. vaccination rates. 
"Moderna (MRNA) anticipates that it will have improved visibility about the expected U.S. market size after seeing full vaccination trends through October 2023," the company said in a regulatory filing. 
The news sent MRNA shares sliding 6.5% on Monday. Also adding to the negative sentiment was rival COVID-19 vaccine maker Pfizer (PFE) last Friday slashing its full year revenue and adjusted earnings per share outlook to reflect lower than expected sales for its COVID products.
Guggenheim Securities said the guidance updates from PFE and MRNA were not surprising. The brokerage observed that while U.S. vaccinations were slightly delayed versus last season, thus far the total doses after about 1 month were trending similarly or slightly above trends from the 2022-2023 season bivalent rollout. 
According to latest trends data from the U.S. Centers for Disease Control and Prevention, coronavirus tests returning positive results fell about 0.8% in the most recent week, while visits to the emergency department fell 17.7%. In total, the country has reported around 6.41M COVID hospitalizations and 1.15M deaths.
Guggenheim "does continue to see COVID-19 vaccinations as a meaningful and durable opportunity, with a combined $18.5-$20.5B in guidance across MRNA, PFE, and NVAX (Novavax) and encouraging survey results," the brokerage said. 
"Ultimately if a similar end season vaccination rate persists, (Guggenheim) expects focus to be on MRNA's market share (currently slightly higher at ~40% vs prior 36%) or international commercial sales to meet commercial sales guidance of $2-4B," it added. 
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