The computer maker's founder and chief executive said the firm will continue to "aggressively execute" its long-term strategy in a deal valued at $24.9 billion.
Robo-Stox is a newly launched index that tracks robotics and automation companies, making it easier to invest in the industry.
Delivering a blow to the Nasdaq, which was accused of bungling Facebook's IPO, Twitter takes another route for its market debut.
The stock exchange went down around noon Eastern, but trading has finally resumed. Meanwhile, the S&P 500 continues to hold onto its gains.
The stock exchange argues that it cannot be sued via class-action suits because of its legal status as a self-regulatory organization.
Since spinning off from 21st Century Fox last year, News Corp. has been on an acquisition spree, snapping up a romance-novel publisher, two online business and now a real-estate listing website.
Commentary: You need to understand a child's innocent passion for Minecraft to know why today's news had such a deep impact across the globe.
CEO Tim Cook delivers on a promise to move into a new product category, making a foray into wearable devices with the Apple Watch. Plus: Bigger-screen iPhones and a mobile service called Apple Pay.
Maybe Salesforce.com CEO Marc Benioff was right in saying that Facebook should have gone public on the New York Stock Exchange.
The technology landscape has changed drastically since Google made its market debut 10 years ago. Google's IPO and its co-founders had a big hand in that evolution.