Amarin Corp Plc (AMRN)

[FlyFishingStocks]

So for small accounts your position has to drop 50% before you get a margin call / forced sale . Larger more experienced accounts 25%

Again ...in 1929 your position had to drop only 10% ...and it was automatically sold thus causing prices to cascade .

Unless you have multiple or larger positions on margin (which most do now a days). Therefore, based on that, margin effect on selling is comparable and in some cases worse. For example widely owned ETFs cause sharp broader index liquidation due to routine margin calls because of the enormity of the debt held
When you add the fact that total margin debt has increased 20 fold in comparison to 1929, you have a horrible situation very comparable to 1929 (in terms of vulnerability to a crash).