Tesla CEO Elon Musk said on Twitter in response to a comment from another user that e-commerce software company Shopify was "great". The comment caused Shopify to rise 3.5% in after-hours trading on the New York stock market.
Elon Musk cofounded the electronic payment firm PayPal and founded the spacecraft company SpaceX and became chief executive officer of the electric-car maker Tesla.
After posting on twitter this month, musk boosted the share prices of at least six companies. The Tesla CEO has more than 43 million followers on twitter. Recipients of Musk's tweets include Gamestop, a US video game retailer, CD Projekt, a Polish video game manufacturer, a Japanese toy company and Etsy, an online market.