http://www.cnbc.com/id/36998463
That sounds hard for me to believe, but thats one rumor. That wouldn't account for the 10% drop but it might have put initiated the drop and then caused other people (and computers) to panic and sell.
[Edit] Actually the stock was down at $39.37 from $61. On normal days PG barely moves at all.
It probably should.
It's really surprising, assuming this is really the cause, that a single letter typo could have such an effect and this has 1) never happened before and 2) not been caught in testing.
http://news.bbc.co.uk/2/hi/business/4512962.stm
In the above case the trader got the price and number of share fields confused.
I will tell you what though - someone... someone, made a lot of money from this. Inadvertently, but more than likely otherwise.
I have actually worked on such software. When a price comes in - a quote - you have a fixed amount of time to respond before it goes stale, usually a few seconds. It's assumed you know what you're doing and that you want to move quickly. Same as operating any other high-powered machinery.
I remember a feature request from a client of ours, we had keyboard shortcuts of k for thousand, m for million and b for billion. They wanted t as well.
Would this rumor create insane profits for some? If that is so, those getting the profits should be investigated. Some employee could have been promissed a large sum in a off-shore account to enter a 'b' instead of an 'm'. It should look like an 'oops' to everyone else while a bunch of HFT algorithms could rake in serious profits as everyone's stop-loss triggers get hit. The employee might get fired, but he the pay-off was large enough, he might not need to work ever again.
Welcome to the world of positive feedback loops, enjoy your stay.
CNBC: Trading Error at Major Firm Blamed for Market Plunge: Sources (Story Developing)
CNBC does NOT know what the cause of this was. The exchanges will come out with some "computer glitch" story or the "fat finger" excuse, but neither of those are true. FWIW, the fat finger excuse is, in a nutshell, some trader accidentally pressing the wrong button on the trading desk.
The market was at a technical support level with various moving averages, timelines, etc. all coming into play. Many people had/have stop losses because the market was/is looking due for a correction. Algo/HFT pounced on this, collectively, and thus the massive drop.
Trust me, if you are buying into what CNBC tells you, you are really missing the truth...