Yahoo was down 50 cents a share, about 4 percent, to $12.15 in trading 12:49 p.m. Eastern Time. Microsoft, meanwhile, had lost another $1.01, 4.5 percent, to $21.29, as the broader market continued its downward plunge.

The Mithras proposal, according to Reuters, proposes Microsoft sell "Yahoo's Asian assets and non-search businesses, extract $3 billion worth of cost savings and receive $2.8 billion of tax benefits, meaning the software giant would pay $10.3 billion for Yahoo's search business."

This latest attempt to get the would-be couple back together comes two days after analysts cut their price targets on Yahoo, whose business is particularly threatened by an expected advertising slowdown. One analyst also said it was "increasingly likely" that Microsoft would renew its bid for Yahoo as shares plummet.

Microsoft and Yahoo made no comment to Reuters on the Mithras proposal. In July, Microsoft execs called the chance of a renewed Yahoo bid "essentially negligible."

In other Microsoft M&A news, Canaccord Adams analyst Peter Misek believes Microsoft has a "standing offer to buy [BlackBerry maker Research in Motion] at $50" a share, according to Reuters.

RIM's shares have dropped from the $130s to the $60s in the past two months and had dipped another $6.16, 10.4 percent, to $52.87 at 12:59 p.m. Eastern Time today.