Anytime Warren Buffett makes a move, the entire investing world watches closely. So it makes sense that investors might be interested in buying shares of Sirius XM (SIRI 0.33%). Buffett's conglomerate Berkshire Hathaway owns 35.4% of the satellite radio operator. For starters, the business collects a recurring revenue stream from subscriptions. In the first quarter (ended March 31), 77% of its overall sales were derived from subscriptions. Management at least has some visibility when it comes to forecasting ...