Hitting the wires moments ago
His decision is definitive
It is too late for him but not for France
His party's situation is a waste
Fillon candidacy is now a dead end
Left runs the risk of being eliminated in the first round
Says Macron's project is weak
The market thinking was that Juppe would step into the breach if Fillon couldn't ride out the scandal he's involved in, and would then push Le Pen further down the rungs in popularity. If Fillon does drop out, that more or less leaves Le Pen with a clear run through to the 2nd round (which is still expected if you believe the polls), and leaves her with a greater chance in the 2nd round. I'm not sure if there are any other players or coalitions that could develop to push other candidates.
The euro is softer across the board after the news with EURUSD dipping under 1.0600 to 1.0591.