U.S. stock-market indexes closed mostly higher on Thursday, as the European Central Bank announced that it plans to end its bond-buying program at the end of the year but pledged to keep rates at present levels until at least next summer.

Stronger-than-expected economic data also lent support to stocks. The Nasdaq Composite Index at record thanks to a rally in technology shares. The index gained 65.34 points, or 0.9%, to 7,761.04. The S&P 500 rose 6.86 points, or 0.3%, to 2,782.49. The Dow Jones Industrial fell at 0.1%. Among the biggest gainers on the S&P 500, Twitter Inc. soared 6.1%.

Dropbox: the best day ever since going public

Dropbox was on pace for its best day since going public Thursday, with massive trading volumes sending shares up roughly 20% at their peak and putting the stock on pace for its best single-day gain in history as it surges to new record levels.

The stock closed up 6.9% on March 26, shortly after the file-storage company's initial public offering. Dropbox shares have been up in the last four trading sessions.

Earlier this week, the company announced updates on its shingled magnetic recording (SMR) storage technology and said it would be the first to deploy this technology "at exabyte scale."

SMR Technology which will increase overall storage density, reduce the company’s physical data center footprint, and provide significant cost savings—without sacrificing performance or reliability. Dropbox will be the first company to test and deploy SMR technology at this scale.

Dropbox anticipates approximately a quarter of its Magic Pocket infrastructure will be on SMR drive capacity by 2019. In the coming months, the company also plans to open source the test software it created in the process, which will let other companies qualify SMR technology for their own enterprise storage environments.

The stock hit an all-time high above $38 after closing Wednesday below $32. Shares were trading at more than 5 times their normal trading volume. Dropbox shares are up more than 70% from their March IPO price of $21.

Etsy’s stock soars towards a new record high

Online crafts marketplace ETSY’s shares soared 9.1% on Thursday after that raised its 2018 revenue growth outlook, citing increased transaction fees.

The company said it now expects 2018 revenue to rise 32% to 34% from a year ago, compared with its previous guidance range of 22% to 24%. The FactSet 2018 revenue consensus of $7.10 billion implies 13% growth.

Etsy, whose platform connects artisans and crafters with online shoppers, also announced new subscription plans and tools for its independent vendors.

"Our revised fee structure will allow us to make more meaningful investments on behalf of our sellers while remaining what we believe is the best value for entrepreneurs looking to start, manage, and grow a creative business," said Chief Financial Officer Rachel Glaser.

The company plans to increase its 2017 direct marketing spend "by at least 40%" in 2018. Shares rose as much as 35% to $44.78, after closing Wednesday at $32.99.