Stocks opened lower Thursday, but moved steadily higher throughout the session, led by a powerful rally in growth stocks. The Dow Jones Industrial Average (DJINDICES:^DJI) and the S&P 500 (SNPINDEX:^GSPC) closed near highs for the day.

Today's stock market

Index Percentage Change Point Change
Dow 0.84% 216.84
S&P 500 1.09% 30.65

Data source: Yahoo! Finance.

Technology stocks led the market, with the Technology Select Sector SPDR ETF (NYSEMKT:XLK) jumping 2.5%. Financials were the only sector in the red; the Vanguard Financials ETF (NYSEMKT:VFH) fell 0.3%.

As for individual stocks, Biogen (NASDAQ:BIIB) announced the failure of its lead Alzheimer's drug, and Levi Strauss & Co. (NYSE:LEVI) soared after going public today.

Columns of stock prices and up arrows.

Image source: Getty Images.

Game over for the most promising Alzheimer's drug

Shares of Biogen got crushed, plunging 29.2% and destroying $18 billion of market value, after the company and Japanese partner Eisai announced they were discontinuing late-stage clinical trials of aducanumab, a drug candidate for treating Alzheimer's disease. An independent data monitoring committee conducted a futility analysis and concluded that the trials were unlikely to meet their primary endpoint.

Aducanumab was designed to reduce abnormal protein deposits called amyloid plaques in the brains of Alzheimer's patients. The plaques are linked to memory loss and functional decline. Data from an earlier trial indicated that the drug reduced the deposits and suggested it slowed clinical decline, but today's result from the trial that wasn't due to read out until early 2020 means that aducanumab just didn't work.

This drug was expected to be a major blockbuster, and was one of the most valuable pipeline assets in the industry. This latest failure in the search for Alzheimer's treatments also casts doubt on two other drugs in Biogen's pipeline that are designed to attack amyloid deposits, eroding hope for Alzheimer's patients and leaving investors to wonder what's next for the biotech giant.

Check out the latest earnings call transcript for Biogen.

Investors welcome Levi Strauss back to the public market

Shares of iconic jeans maker Levi Strauss were snapped up in the company's initial public offering, opening at 30.7% above the offering price of $17 and closing up 31.8% at $22.41. The stock was offered above the range of $14 to $16 that the company had anticipated 10 days ago and puts the company's value at about $8.8 billion.

The IPO raised proceeds of $624 million, most of which will go to existing shareholders. The company will receive proceeds of $161 million, plus another $94 million when underwriters exercise their option for additional shares.

Levi Strauss grew fiscal 2018 revenue by 14% to $5.6 billion and had operating income growth of 15%. The 166-year-old company is seeing low-single-digit growth of its core business in men's pants, and is having success with its expansion strategy into tops and women's clothing, which saw sales grow 29% to $1.6 billion last year. That recent success and a market that is warming up to IPOs was the perfect environment for the stock's debut today.