LONDON—The blockage of the Suez Canal for nearly a week will result in a “large loss” for Lloyd’s of London, its chairman said on Wednesday, as the insurance market recorded a 900 million pound ($1.2 billion) pretax loss in 2020 due to the COVID-19 pandemic. The Canal is working to clear the backlog after the refloating this week of a stranded giant container ship. The blockage threw global supply chains into disarray. Bruce Carnegie-Brown told Reuters it was too early to estimate the exact loss, but “it’s clearly going to be a large loss, not just for the vessel but for all of the other vessels that were trapped and unable to get through.” He added this could mean a loss for Lloyd’s of around $100 million or more. Liability insurance claims for ships and cargo impacted by the delay are expected to fall initially to the container ship Ever …