 BioCardia Inc OTCMKTS:BCDA gapped down prior to trading on Thursday . The stock had previously closed at 2.20, but opened at 2.12. BioCardia shares last traded at 2.22, with a volume of 501,462 shares changing hands. Separately, Maxim Group began coverage on BioCardia in a research report on Friday, May 1st. They issued a buy ... 