Sirius XM (NASDAQ:SIRI) keeps putting its money where its mouth is.

The satellite radio provider is expanding its aggressive buyback efforts, earmarking another $2 billion to spend in stock repurchases. Sirius XM is already $1.6 billion into the original $2 billion plan it announced 10 months ago, and it will wrap that up shortly. This morning's announcement also reveals that Sirius XM will be buying back $500 million of common stock held by majority stakeholder Liberty Media (NASDAQ:FWONA). Those shares will be purchased in three installments through April at a predetermined price that will be a discount to its volume-weighted average following its third-quarter report. 

That transaction alone will more than satisfy last December's $2 billion buyback authorization, so this hasn't just been lip service on the media darling's behalf.

Everything seems to be going right for Sirius XM these days. The stock hit a fresh six-year high earlier in the week when it hit the previously elusive $4 mark in intraday trading. 

From $4 as a share price to what is now $4 billion in buyback authorizations, Sirius XM has come a long way from when it was teetering on the brink of bankruptcy four years ago.

It's a good thing that Sirius XM acted on its original authorization sooner rather than later. It has been able to retire more than 476 million shares at an average price of roughly $3.36. It's not going to get that kind of deal these days, and longtime investors are more than happy to see the second buyback snap up fewer shares at higher price points.

How will Sirius XM pay for its new shopping spree?
Sirius XM will fund the buyback through cash, future cash flow from operations, and new debt. The satrad star isn't made of money, but it is raking it in these days. Back in July it was targeting $915 million in free cash flow this year alone. Given the scalable nature of its model and its ability to keep programming costs in check -- unlike other content broadcasters -- every new subscriber really is more valuable than the one that came before. As long as Sirius XM's subscriber tally keeps moving in the right direction Sirius XM has the flexibility to generate more money that it can return to shareholders through repurchases. 

Taking a few of Liberty Media's chips off the table will also help ease fears of what can happen to the stock if Liberty Media were to spin off its stake and bloat the float. 

It's a smart move for Sirius XM as long as it doesn't take on too much debt to eat its own cooking.