Twitter worth $8.5 billion more after Elon Musk’s investment sends stock on record run

Shares of Twitter Inc. rocketed to their biggest single-day gain ever Monday, after it was disclosed that the “Technoking” of Tesla Inc., Elon Musk, had acquired a large stake in the social-media company.

Twitter stock TWTR ran up 27.1%, the biggest one-day percentage gain since the social-media company went public in November 2013. The previous record rally was 21.4% on Sept. 23, 2016. The increase added roughly $8.53 billion to Twitter’s market capitalization, also a record for a single day, according to Dow Jones Market…