Stocks opened higher on news that an increase in tariffs on Chinese goods will be delayed, but drifted lower during the session. The Dow Jones Industrial Average (^DJI 0.23%) and the S&P 500 (^GSPC 0.80%) both posted modest gains.

Today's stock market

Index Percentage Change Point Change
Dow 0.23% 60.14
S&P 500 0.12% 3.44

Data source: Yahoo! Finance.

Biotech shares jumped following news of some big deals, with the SPDR S&P Biotech ETF (XBI 3.16%) soaring 4.4%. Gold stocks slumped; the VanEck Vectors Gold Miners ETF (GDX 3.68%) fell 1.3%. 

As for individual stocks, Roche Holdings (RHHBY 1.07%) announced it is buying Spark Therapeutics (ONCE), and Berkshire Hathaway (BRK.A -0.42%) (BRK.B -0.56%) released its annual shareholder letter over the weekend.

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Image source: Getty Images.

Roche is paying up for gene therapy

Shares of gene therapy specialist Spark Therapeutics catapulted 120.1% to $113.48 after Swiss pharmaceutical giant Roche Holdings announced it is buying the company for $114.50 per share in an all-cash deal worth $4.3 billion. The price is a 122% premium to Friday's closing price and 19% above Spark's all-time high of $96.59 last July.

Spark specializes in gene therapies for genetic diseases, and was the first company to receive FDA approval for such a treatment in 2017, when Luxturna was approved as a one-time therapy for a rare disease that causes blindness. The biggest prize for Roche on the near-term horizon, though, is Spark's gene therapies for hemophilia A and hemophilia B, which are in late-stage clinical trials. Those assets will complement Roche's current entry into the hemophilia market, Hemlibra.

The deal still needs approval from Spark shareholders and regulatory authorities, but Roche, which acquired a genetic testing company last year and biotechnology pioneer Genentech a decade ago, expects the transaction to close in the second quarter.

Check out the latest Spark Therapeutics earnings call transcript.

Berkshire Hathaway reports higher operating earnings

One event that is highly anticipated in the investment community is the release of Berkshire Hathaway's annual letter to shareholders, which is penned by Warren Buffett himself. The 2018 edition reported a big gain in operating earnings and a change in the way the company will report results. The stock finished up 0.2%.

Berkshire reported a loss of $25.4 billion, but that came about because under accounting rules, the company must report paper losses from the value of publicly traded stocks in its portfolio in current earnings. Buffet encourages shareholders to focus on operating earnings, which for the year came in at $24.8 billion, exceeding the previous high set in 2016 by 41%.

Buffett said that the company will depart from its long tradition of reporting book value, since over time, Berkshire will be "a significant repurchaser" of its own shares, which causes a divergence of the metric from the company's intrinsic value.

Looking forward, Buffett said that prices for businesses with good long-term prospects are "sky high," meaning Berkshire will probably continue to expand its holdings of marketable securities, rather than buy companies outright.