Reply #4: Sounds like a repeat of the 1965 Northeast Blackout

[Xipe Totec]

But with stock trades this time instead of electricity:

The cause of the failure was human error that happened days before the blackout, when maintenance personnel incorrectly set a protective relay on one of the transmission lines between the Niagara generating station Sir Adam Beck Station No. 2 in Queenston, Ontario. The safety relay, which is set to trip if the current exceeds the capacity of the transmission line, was set too low.

As was common on a cold November evening, power for heating, lighting and cooking was pushing the electrical system to near its peak capacity, and the transmission lines heading into Southern Ontario were heavily loaded. At 5:16 p.m. Eastern Time a small surge of power coming from Lewiston, New York's Robert Moses generating plant caused the misset relay to trip at far below the line's rated capacity, disabling a main power line heading into Southern Ontario. Instantly, the power that was flowing on the tripped line transferred to the other lines, causing them to become overloaded. Their protective relays, which are designed to protect the line if it became overloaded, tripped, isolating Adam Beck from all of Southern Ontario.

With no place else to go, the excess power from Beck then switched direction and headed east over the interconnected lines into New York State, overloading them as well and isolating the power generated in the Niagara region from the rest of the interconnected grid. The Beck and Moses generators, with no outlet for their power, were automatically shut down to prevent damage. Within five minutes the power distribution system in the northeast was in chaos as the effects of overloads and loss of generating capacity cascaded through the network, breaking it up into "islands". Plant after plant experienced load imbalances and automatically shut down. The affected power areas were the Ontario Hydro System, St Lawrence-Oswego, Western New York, Upstate New York, New England, and Maine. With only limited electrical connection southwards, power was not affected to the Southern States. The only part of the Ontario Hydro System not affected was the Fort Erie area next to Buffalo which was still powered by the old 25 Hz generators. Residents in Fort Erie were able to pick up a TV broadcast from New York where a local backup generator was being used for transmission purposes.

http://en.wikipedia.org/wiki/Northeast_Blackout_of_1965

We continue to build more complex and interconnected systems, whose behavior is becoming more chaotic and unpredictable.