Microsoft has renewed discussions with Yahoo for an acquisition or a partnership of some sort, according to reports in the New York Post and the Wall Street Journal.

A year ago, the two companies talked about becoming a greater competitor to Google, but those discussions ended without resolution. These new talks are in early stages, but Wall Street still took the news with enthusiasm, as Yahoo shares soared nearly 17 percent after the market opened. Google shares fell slightly. The Post cites sources that put a $50 billion price tag on Yahoo.

The landscape for online advertising is even more competitive than it was a year ago, and both Yahoo and Microsoft have had management changes since their earlier talks, the Journal reports. Last month, Google outbid Microsoft and Yahoo for the purchase of online advertising firm DoubleClick.

A Microsoft-Yahoo merger makes sense for both companies. Microsoft has struggled to keep up in the online advertising market, and Yahoo would benefit from the software giant's technical expertise.

The Journal says that Microsoft likely wants to buy Yahoo outright, but that a possible outcome would be for Microsoft to spin out its online unit into Yahoo in exchange for a stake in the company.