Two of Navios Maritime Containers' largest shareholders have alleged that the company lied to get them to invest before using a potentially phoney conversion plan to undercut their rights and enrich chief executive Angeliki Frangou.

On Monday, Mangrove Partners and 683 Capital Partners — which together own 16.1% of the Nasdaq-listed company — accused the boxship owner of fraud in its 2018 direct listing, a new allegation in a legal dispute that began in March.