Shares of Sirius Satellite Radio Inc. (NASDAQ: SIRI) and XM Satellite Radio Holdings Inc. (NASDAQ: XMSR) jumped on Tuesday after a proposed all-stock merger between the companies.

Sirius shares rose 6.5 percent, or 25 cents to $3.95, while XM shares went up 12.8 percent, or $1.79, to $15.77 in afternoon trading.

The proposed merger, announced Monday, would see the two major satellite radio companies combine to create a firm with over 14 million subscribers. One factor that will likely play a large role in deciding the fate of the combination is whether the U.S. Department of Justice will approve the deal out of concern that competition would diminish as a result of the deal.

Executives at both companies have said they want to work with regulators to assure their approval.

The agreement calls for XM shareholders to receive 4.6 Sirius shares for each XM share, or a 21.7 percent premium on both companies’ closing prices on Friday.

The firms say that the merger will allow for savings estimated to be between $3 billion to $7 billion.

One group opposed to the deal is the National Association of broadcasters. It’s Executive Vice President, Denis Wharton says the government has a history of opposing monopolies. The NAB would be “shocked” if the U.S. officials approved the merger, he said.