Dear all, 

I recently received a job offer at a different firm. After telling my manager at my current firm that I will be taking the new job he spent over a week trying to convince me to stay. Nothing that he offered convinced me enough to want to stay and in his final attempt he threaten to call my new firm and tell them not give me the job and also that if I handed in my resignation letter before he said I could he would put a mark on my U4. 

Yesterday I handed my resignation letter to our licensing coordinator without telling my manager. She assured me that there is nothing that he can do.

Is there anyway he can "mark" my U4 even if I did nothing wrong and or call my new employer to convince them not to hire me ?