Looks like Mangrove have given up the fight. They have filed with the SEC that they have tendered all their stock in the Dutch auction at 1.68 per share, a loss of about 6 cents per share for them.
They still oppose the transaction with BTA, but that seems hollow under the circumstances. Or maybe a threat to make sure their offer is accepted. They also sugest the NABI share price will tank after the auction. Maybe down to BTA's level.