Boeing stock is set to plunge again after Australia joins Singapore in suspending 737 Max flights

• Boeing is set to tumble again when markets open in New York on Tuesday. The stock is down 1.8%, or about $4.1 billion, in premarket trading.
• Australia and Singapore became the latest to suspend use of all Boeing 737 Max planes. Mexican, Brazilian and Argentine carriers also grounded aircraft.
• The stock decline in premarket trading is chipping into gains in Dow futures, which are mainly flat.

Boeing is set to tumble again in New York trading when markets open on Tuesday, following a 5.3% plunge on Monday, after Australia and Singapore became the latest to suspend use of all Boeing 737 Max planes.

Boeing's stock is down 1.8% in premarket trading, equivalent to a drop of about $4.1 billion from Boeing's market capitalization.

Mexican, Brazilian and Argentine carriers also said they will ground Boeing 737 Max planes, the Wall Street Journal reported. The countries follow Indonesia and China in grounding the jets after the crash of Ethiopian Airlines Flight 302 on Sunday, which killed all 157 people on board.

The WSJ said that some 40% of all the 737 Max planes that Boeing has delivered since May 2017 are now suspended.

"Several airlines and regulators have grounded the Max 8 model, but Australia and Singapore are understood to be the first countries to ban planes from across Boeing's Max fleet," the Guardian wrote on Tuesday.

The stock decline in premarket trading is chipping into gains in Dow futures, which are mainly flat as of 8:54 a.m. in London (4.54 a.m. in New York). S&P 500 and Nasdaq futures are up about 0.2%.

Read more: Some countries and airlines have grounded the Boeing 737 Max 8 after a 2nd crash involving the plane killed 157 people - here's who's taken action so far

The crash has prompted some countries and airlines to halt their fleets while Boeing investigates whether there's a link between Ethiopia's disaster and the crash of Lion Air Flight 610, which plunged into the Java Sea 12 minutes after takeoff in October.

A Boeing representative told Business Insider in an email earlier this week that a Boeing technical team would be traveling to the crash site in Ethiopia to provide technical assistance with the investigation. The Lion Air crash is still being investigated as well.

Graham Rapier contributed to this report.

Get the latest Boeing stock price here.