If you're already unemployed, it's possible to keep your allowance longer for a business start-up or takeover.
It's also possible to sign a “rupture conventionée”, which entitles you to unemployment benefits.
But no, if the employee resigns, he or she is not entitled to unemployment benefits, nor to business start-up assistance.
the French system is generous, but not as generous.
First, there are some "protected classes" of resigning that allow you to be eligible for unemployment right after you resign, for example: moving to follow your spouse, resigning less than 3 months after having been laid off, going back to study or... creating a company!![1] :).
Second, you are entitled to unemployment benefits even if you resign without "a good reason". The issue is that you can only request your benefits 4 months after having resigned. This leads to many people believing that you just do not get anything if you resign; because who wants to eat the 4 months of no income?
This 4 months waiting period is not advertised at all, and my complotist self believes it might be on purpose; if you don't know about it and don't request it, that's less money for the government to spend :^).
[1] Conditions apply (having worked uninterrupted for the last 5 years)
It's not only CAC40, it's part of some collective bargaining agreements which apply to whole sectors (e.g. SYNTEC which applies to all consulting and most IT companies).