Carnival Corporation is to sell stock worth up to $1.5 billion on the back of market optimism that an effective vaccine for Covid-19 is on the horizon.

The world’s largest cruise ship operator has already raised more than $10 billion since the start of the pandemic in March, which forced the abandonment of all global sailings.

The planned share sale was detailed in a filing to the US Securities and Exchange Commission.

Responding to this week’s announcement that a vaccine developed by Pfizer BioNTech could prevent 90% of people from getting Covid-19, a Carnival Corporation spokesman said: “This is a very positive development for the world, and, of course, our company and our brands, as well as the cruise industry.

“It is too early at this point to determine the impact this may have on the conditional sail order in the US, if any.”

Meanwhile, Tui declined to comment on speculation that it was considering approaching the German government for a third bailout of up to €1.8 billion.

Europe’s biggest tour operator has already received €3 billion of state-backed loans in two tranches this year.

Reuters reported sources as saying the current talks are focusing on strengthening the company’s capitalisation.

Tui said last month that it was continuing to evaluate various measures “to achieve an optimal balance sheet” inculuding a capital increase “significantly lower” than €1 billion-€1.5 billion mentioned in press reports.

At the same time, Lufthansa raised €600 million through a convertible bond offering. It increased the size of the deal after strong demand from investors.

The German airline group’s finance executive vie president Wilken Bormann said: “The transaction proves that Lufthansa still has access to attractive financing de­spite the corona pandemic and highlights the trust in Lufthansa as a borrower and the group’s good international reputation.

“It is another successful step towards re­financing existing liabilities and government stabilisation measures.“

The group said had €10.1 billion of cash at its disposal at the end of September, including state bailout funds in Germany, Switzerland, Austria and Belgium which have not yet been utilised.

American Airlines plans to sell 38.5 million shares to raise $508 million plus the option for 5.78 million shares to be available to the underwriter of the offering.

The airline, which last month reported a $3.1 billion third quarter pre-tax loss, said expects to use the proceeds from the share offering for “general corporate purposes and to enhance the company’s liquidity position”.