IB didn't even know crude oil price could go negative a few months back, no one at IB read the CME memo. Thats not very professional either. Back to AMP, i reckon they also got burnt during the Crude oil negative flash crash. Obviously not to the extent of IB losses. But since that event they (AMP) have been more jumpy regarding margin.
Believe me, this is good that AMP do this, change mind quickly. Even though it looks a bit unprofessional. When IB increase margin, they don't put it back down for ages, even after volatility goes back down. IB used to have a policy: When VIX goes above 30 remove day trade margin. Reinstate day margin when VIX falls below 20. Yeah they used two different numbers. Completely illogical. It could be months before VIX fell back below 20.
This jump happened just out of nowhere. Then volatility is increasing every week as the market is highly affected by the COVID-19 conditions. If this troublesome situation prolonged, there would be increased risk of extreme volatility, giving a severe hit to the market.
I am focusing on the market regularly from some time and I can say that I was not expecting this kind of jump. We all are aware of how the market has gone volatile in the COVID-19 situations and I can say that there are quite chances that the market will hit the condition of extreme volatility.