Key Takeaways SiriusXM shares rallied Monday after Warren Buffett’s Berkshire Hathaway raised its stake in the satellite radio company.Berkshire Hathaway now holds a stake of nearly one-third in SiriusXM.

Berkshire hiked its bet after Liberty Media completed its deal in early September to combine its tracking stocks with the rest of the entertainment company.

This followed Liberty Media's tracking stocks with SiriusXM in early September and a restructuring of Malone's media assets while also spinning out the Atlanta Braves a company in which Berkshire owns stakes.

Warren Buffett's Berkshire Hathaway now has a stake of about 32.5% in Sirius XM’s publicly traded stock, having become the top holder last month.

Warren Buffett’s company apparently is taking advantage of the weakness in the stock, which is down 50% this year.

Warren Buffett’s investment firm, Berkshire Hathaway, has increased its stake in Sirius XM Holdings to 32%. The company purchased roughly 3.6 million shares for about $87 million in separate transactions.