On the heels of reports last week that AT&T wants to renegotiate the terms of a five-year partnership with Yahoo, the latter's share price dropped over five percent, reports The Financial Times.

The current deal is estimated to be worth about $200 million a year in revenue for Yahoo from the co-branded AT&T/Yahoo broadband service. The 5.2 percent drop in share price knocked off approximately $8 billion in market value for Yahoo.

The story hints at a mindset at AT&T that it holds the stronger negotiating position and may in fact be able to demand fees from Yahoo. AT&T has been gaining strength as it engages in a series of mergers and acquisitions that almost bring it back to the level of Ma Bell.

On the other hand, despite what had been a recent uptick, Yahoo's stock price has slipped in the past year over concerns that its share of the advertising market is not strong enough to support it and that its business strategy is unfocused.