Warren Buffett's Berkshire Hathaway plows $267 million into Liberty SiriusXM, boosting its bet on Howard Stern and Pandora

• Warren Buffett's Berkshire Hathaway spent $267 million on Liberty SiriusXM stock this week.
• The investor's company now owns almost 20% of the Liberty Media subsidiary's "A" shares.

Warren Buffett's Berkshire Hathaway plowed $267 million into Liberty SiriusXM on November 1, SEC filings show.

The famed investor's company snapped up 5.3 million of the Liberty Media subsidiary's "A" shares at an average price of $50. The purchases boosted its holding by 36% to 20.2 million shares, or nearly 20% of the "A" shares outstanding. The enlarged stake was worth just over $1 billion as of Wednesday's close.

Berkshire also owned about 43 million of Liberty SiriusXM's "C" shares at the last count, worth roughly $2.2 billion today. Combine the conglomerate's two holdings and it owns roughly 19% of the media group.

Both the "A" and "C" shares have jumped in price by about 25% this year. They rose as much as 3% on Thursday.

Liberty Media divides its business interests into three groups, each with an associated stock. Liberty SiriusXM owns 78% of SiriusXM - which counts Howard Stern among its hosts, and owns music-streaming service Pandora - and has stakes in Live Nation and IHeartMedia. Meanwhile, Liberty Braves owns the Atlanta Braves baseball team, and Liberty Formula One owns the motorsports business.

Berkshire's purchases this week suggest it's bullish on SiriusXM. The broadcaster's revenue grew 10% year-on-year to $6.4 billion in the nine months to September 30, driving its net income up 23% to $995 million. The company signed up a net 1.1 million paying subscribers in the period, expanding its total subscriber base to 32 million.

Buffett and his team will disclose the contents of their US stock portfolio as of September 30 later this month. Berkshire's third-quarter earnings, due Saturday, will reveal how much it spent on equities in the period, and how much it pocketed from stock sales.