Stockmarket deal maker Tolga Kumova said fund managers who he previously worked with stopped returning his calls, after multiple tweets from self-styled penny stock cop Alan Davison, better known as Stock Swami, allegedly accused him of repeatedly engaging in insider trading, which he said painted him as a criminal.

In the Federal Court of Australia on Wednesday before Justice Michael Lee, Mr Kumova a former Financial Review Young Rich lister took the stand to give evidence in a defamation battle he launched against Mr Davison.