Hurricanes almost always set off an orchestrated dance on Wall Street before they make landfall, with shares of property and casualty insurance companies dumped in favour of companies that sell construction supplies or portable generators.

That routine began a week ago, though Hurricane Florence appears to be turning up the volume this time.

The last time a hurricane of this size struck the middle of the East Coast, Texas Instruments had just introduced the first transistor radio.

Since then, the region has been developed heavily and the potential damages may be exponentially higher.

Karen Clark & Co, which produces models for catastrophes, said that if 1989’s Hurricane Hugo had hit South Carolina in 2012, just 23 years later, insurance losses would have more than doubled to $10bn (£7.7bn) when development and inflation are factored in.

Forecasting where a hurricane will hit and with what level of force is always tricky and there is a long history of false alarms. But the likelihood that Hurricane Florence will collide with the Carolinas and neighbouring states has created a sustained sell-off of major property and casualty insurance companies and the companies that insure the insurers.

Allstate Corp had been in decline for three days, as has Travelers Cos, though those shares appeared to stabilise on Tuesday.

Property and casualty insurance investors “are still keenly aware of significant losses from Hurricanes Harvey, Irma, and Maria in 2017,” wrote Kai Pan and Michael Phillips, analysts with Morgan Stanley. “We expect Florence to weigh on P&C (re)insurance stocks as it moves closer to mainland US.”

Allstate has a 6.9 per cent market share for home, auto and commercial property coverage in the Carolinas and Virginia, according to Morgan Stanley. Berkshire Hathaway has a market share of 5.6 per cent, and Travers is 4.3 per cent.

Hurricane Florence hits the US East Coast Show all 20 1 /20 Hurricane Florence hits the US East Coast Hurricane Florence hits the US East Coast Barmen protect their business from the storm and the opportunists Getty Hurricane Florence hits the US East Coast Many supplies have run out as Hurricane Florence approaches in Nichols, South Carolina AP Hurricane Florence hits the US East Coast Hurricane Florence seen from space on September 12 AP Hurricane Florence hits the US East Coast Students of East Carolina University's Coastal Storms class use anemometers to measure wind speeds at Union Point Park in New Bern, North Carolina AP Hurricane Florence hits the US East Coast Rescue workers are on the scene in James City, North Carolina Getty Hurricane Florence hits the US East Coast Sixteen hours before Florence even hits land, the Neuse River bursts its banks and floods New Bern, North Carolina Alamy Hurricane Florence hits the US East Coast Volunteer rescue workers help three children out of their flooded home in James City, North Carolina Getty Hurricane Florence hits the US East Coast A boardwalk is damaged in Atlantic Beach on North Carolina's coast Getty Hurricane Florence hits the US East Coast Union Point Park in New Bern is closed Reuters Hurricane Florence hits the US East Coast A child sits in Conway High School, which is being used as an evacuation centre in South Carolina AFP/Getty Hurricane Florence hits the US East Coast Locals voice their disapproval of the storm in Atlantic Beach, North Carolina Getty Hurricane Florence hits the US East Coast Volunteer rescue workers help children from their flooded home in James City Getty Hurricane Florence hits the US East Coast A man floats down his street in a metal tub after the Neuse River burst its banks in New Bern, North Carolina Getty Hurricane Florence hits the US East Coast Electric lines are affected in Wilmington, North Carolina Alamy Hurricane Florence hits the US East Coast Floods in New Bern, North Carolina as Florence approaches Alamy Hurricane Florence hits the US East Coast Waves crash over a pier on Atlantic Beach in North Carolina as Hurricane Florence approaches AP Hurricane Florence hits the US East Coast Hurricane Florence is seen from the International Space Station as it churns in the Atlantic Ocean towards the east coast of the US NASA/Reuters Hurricane Florence hits the US East Coast This NOAA/RAMMB satellite image taken on September 10, 2018, shows Hurricane Florence off the US' east coast in the Atantic Ocean AFP/Getty Hurricane Florence hits the US East Coast In this NOAA satellite handout image, Hurricane Florence is shown travelling west and gaining strength in the Atlantic Ocean southeast of Bermuda on September 10, 2018 Getty Hurricane Florence hits the US East Coast Firefighters rescue people by boat in New Bern, North Carolina Getty

As of 5pm on Tuesday, Florence was centred 785 miles (1,260kms) southeast of Cape Fear, North Carolina, moving west-northwest at 17mph (28kph).

The centre of the titanic storm is expected to meander on Thursday, Friday and Saturday over a stretch of coastline saturated by rising seas, inundating several states and triggering life-threatening floods.

Seven-day rainfall totals are forecast to reach 10in to 20in (25 to 50cm) over much of North Carolina and Virginia, and even 30in in some places. Combined with high tides, the storm surge could swell as high as 12ft (3.7m).

Insurers, of course, have built up war chests and insured their own potential losses given the severity of the storms that have been striking the coastal United States.

Pan and Phillips point out that even with losses exceeding $140bn (£107bn) last year, the insurance industry remains well-capitalised. How to put a price on the destruction and how those companies will secure funding going forward is a topic of discussion this week at the annual, global reinsurance conference in Monte Carlo, where the analysts are in attendance.

But early estimates are emerging, based on each $1bn (£768m) in covered damages.

North Carolina has the highest property and casualty-insured premiums of the three states at $16bn (£12bn), followed by Virginia at $13.6bn (£12bn), and South Carolina at $9.5bn (£7bn), according to Citi.

“In North Carolina, we estimate Travelers losses would be about $42m (32m) for each $1bn in insured losses, followed by Allstate at $37m (£28m), Chubb at $25m (£19m) and Progressive at $21m (£16m),” wrote Citi analyst James Naklicki.

On the other hand, companies that help people ride out a storm, or clean up afterward, are having an exceptional week.

Shares of Generac Holdings Inc, which sells generators, are up 8 per cent in just the past week. Shares of Home Depot Inc and Lowe’s Cos are both up about 4 per cent in the same period.