U.S. stock futures were sharply lower in early trading on Friday after Johnson & Johnson said its one-dose coronavirus vaccine showed less effectiveness in some regions.
Futures for the Dow Jones Industrials blundered 365 points, or 1.2%, to 30,141.
Futures for the S&P 500 sank 41.5 points, or 1.1%, at 3,737.75.
Futures for the NASDAQ Composite faltered 135.25 points, or 1%, to 13,050.75.
It's been a volatile week on Wall Street. The Dow lost more than 600 points on Wednesday, suffering its worst selloff in three months. Then the blue-chip benchmark rebounded by 300 points on Thursday amid a broad market rally. All three major averages have lost at least 1% this week.
Futures accelerated losses after JNJ said its one-dose vaccine demonstrated 66% effectiveness overall in protecting against COVID-19. The vaccine was 72% effective in the United States, 66% in Latin America and 57% in South Africa after four weeks, according to the late-stage trials.
Heightened speculative trading by retail investors continued to unnerve the market. Shares of GameStop doubled in premarket trading after Robinhood said it would allow limited buying of the stock and other heavily shorted names after restricting access the day before. Robinhood raised more than $1 billion from its existing investors overnight, in addition to tapping bank credit lines, to ensure it had the capital required to allow some trading again in the volatile stocks.
Investors are concerned that if GameStop continues to rise in such a volatile fashion, it may ripple through the financial markets, causing losses at brokers like Robinhood and forcing hedge funds who bet against the stock to sell other securities to raise cash.
There are also fears that the GameStop mania is a sign of a larger bubble in the market and that its unraveling could also cause turbulence and hit retail investors hard. Several e-brokers on Thursday took steps to curb the deliberate buying of highly speculative names. A number of lawmakers also called for an investigation into the chaotic trading.
A wave of retail traders have been motivating each other on the red-hot WallStreetBets Reddit forum to pile into the most hated names by hedge funds, creating massive short squeezes in the stocks. GameStop has soared more than 900% in January, while AMC Entertainment has rallied over 300% this month.
Strong corporate earnings continued to roll in after the bell on Thursday. Payments giant Visa, Mondelez, Western Digital and Skyworks Solutions all rose in extended trading after reporting better-than-expected profits and sales for their quarterly results.
Caterpillar, Chevron, Eli Lilly and Honeywell report earnings before the bell on Friday.
Elsewhere on the vaccine front, biotech firm Novavax said Thursday that its coronavirus vaccine was more than 89% effective in protecting against COVID-19 in its phase three clinical trial conducted in the United Kingdom.
Overseas, in Japan, the Nikkei 225 slipped 1.9%, while in Hong Kong, the Hang Seng index fell 0.9%.
Oil prices picked up 14 cents to $52.48 U.S. a barrel.
Gold prices zoomed $28.50 to $1,866.40 U.S.