Travel stocks in particular are down...
Travel stocks endured the bulk of the losses on the FTSE 100 with IAG - the owner of British Airways, easyJet and Flybe all losing around 3% of their market value in the first few minutes of trading.
TUI - the company behind Thomson and First Choice - was 1.2% lower while Thomas Cook was down 1.3%.
Elsewhere, shares in French hotels operator Accor fell 4% while Air France-KLM were more than 1.6% off.
The lorry attack, in Nice, was the latest to knock investor confidence in the holiday sector - an industry about to embark on its busiest time of the year with school summer holidays set to peak in Europe.
Witnesses described how crowds, who had been watching a Bastille Day fireworks display, ran for their lives as French nationals and holiday-makers were struck by the vehicle.
Earlier deadly attacks in Egypt, Turkey, France and Belgium had similar effects on share prices - which remain under pressure over fears that slowing economies will further hit demand for foreign travel.
British Airways confirmed last month that it had no plans to resume flights to Sharm el Sheikh this coming winter despite Egypt insisting its security had been improved since the bombing of a Russian passenger jet last year.
Other operators have kept their options open but said they will only resume services once Government travel advice allows.
Sharm - once a popular winter destination for Europeans - has been likened in recent times to resembling a ghost town amid a collapse in the country's wider tourism industry.
A report last week, in the wake of the UK's vote to leave the EU, claimed the referendum had already resulted in UK consumers adjusting their summer holiday plans abroad, with 3% even opting to cancel.
Travelzoo also warned of higher costs ahead in the price of holidays as operators faced the prospect of the effects of a weak pound.