By Nivedita Balu (Reuters) – Tesla Inc top boss Elon Musk revealed a 9.2% stake in Twitter Inc, worth nearly $3 billion, making him the micro-blogging site’s largest shareholder and triggering a more than 25% rise in the company’s shares. Musk’s move comes close on the heels of his tweet that he was giving a “serious thought” to building a new social media platform, while questioning Twitter’s commitment to free speech. A prolific Twitter user, Musk has over 80 million followers since joining the site in 2009 and has used the platform to make several announcements, including teasing a go-priva…