Goldenport, one of the last shipping companies left on the London Stock Exchange, has delisted from the market and sold off six of its remaining eight vessels for $1 (69p) each.

The giveaway reflects the most dismal shipping conditions in decades, caused by economic slowdown in China combined with an oversupply of vessels due to a building spree during a previous boom.

The Greek owners are looking for buyers for two remaining vessels and are taking Goldenport off the stock market, saying it no longer makes sense to list shares which have dropped from highs of £50 in 2007 to less than 1.5p.

John Dragnis, the chief executive of Goldenport, said the company’s lenders and shareholders had agreed to the fleet sell-off at a time when the company had debts of more than £100m to RBS and other banks. “The value of the vessels is less than the value of the loans due to extreme market conditions.”

He added: “Dry bulk vessels generally have fallen in value by around 60% over the last year partly because of extreme oversupply and partly because of low demand for coal as China moves towards renewable energy to curb [carbon] emissions.”

Dragnis said family and management controlled almost 60% of Goldenport and had suffered along with all other shareholders from the downturn. The Athens-based shipowner declined to predict when market conditions might pick up although he thought it could be between one and three years.

Goldenport would continue as a private company but admitted in a statement to the stock market that its cash reserves had been “drained”. It added: “The prevailing market conditions are probably the worst of the last 30 years with the Baltic Dry Index dropping to historic lows, and average daily hire rates falling below even a vessel’s daily operating expenses.”

The six ships already sold have been transferred to the ownership of small companies owned by the Dragnis family which originally set up Goldenport and brought the company to the stock market.

The announcement of plans to float in 2006, when the shipping markets were riding high on China’s fast-tracked industrialisation programme, boasted of the value to come.

Goldenport was active, it said, in two main segments of the international shipping market, containers and dry bulk “enhancing stability of revenue streams”. It added that there would be “highly predictable cash flows due to long term contractual arrangements with large established charter counterparties”.

The boom before 2005 encouraged shipbuilding – particularly in China – but caused huge overcapacity as the market turned to bust after 2012. All but one of the Goldenport vessels themselves were built in 2010 and 2011.

Richard Fulford-Smith, the founder of the Affinity shipbroking firm and a leading figure in the London maritime scene, said the bulk shipping markets were in “a sad state” and there could be more bankruptcies and exits before any bounce back. Fulford-Smith, 60, added: “I will probably be retired by the time there is any real recovery.”