The Dow tumbled nearly 150 points this afternoon after a fake tweet about White House explosions was posted from the AP's hacked twitter account. Markets recovered almost completely after the AP clarified that the news was false.
posted by Westringia F. on Apr 23, 2013 - 134 comments

Invented by Charles Dow in 1896, The Dow Jones Average ("The Dow") is perhaps the most widely known metric of equity market behaviour. Calculated as a price weighted average of thirty stocks, The Dow is generally eschewed by professional investors who prefer the broader S&P 500, a so-called market capitalisation weighted index consisting of 500 stocks. Regardless, proponents of the Dow claim its simplicity, long history and careful design as a reliable proxy of US economic activity as points in its favour. But can they now claim predicability as well? [more inside]
posted by Mutant on Oct 23, 2010 - 19 comments

High frequency trading crop circles. Automated trading is flooding stock exchanges with nonsensical orders making odd patterns like The Knife at millisecond scales. Bugs, emergent phenomena, or market jamming strategies? No one seems to know.
posted by Nelson on Aug 7, 2010 - 108 comments

Academic discussions of stock markets frequently reference The Efficient Markets Hypothesis; an idea that share prices are fairly valued, their prices reflecting all available information. However folklore such as "Sell in May and go away", which proved prudent in 2007, clashes with this theory. [more inside]
posted by Mutant on May 15, 2008 - 11 comments

The Motley Fool's new CAPS stock-picking system keeps track of your stock picks and whether they outperformed or underperformed the market. Then everyone's picks are aggregated, weighted by the quality of their past records, to rank individual stocks. Here's how it works. (more inside)
posted by ikkyu2 on Oct 4, 2006 - 13 comments

"Buy Stock in Ipods. Or Da Vinci Codes." Steve Odom's Smarkets is a web-based stock trading game (and market experiment) based on Amazon.com sales rank. (via jayisgames)
posted by selfnoise on Dec 22, 2005 - 8 comments

Consensus View
New Yorker columnist James Surowiecki's book The Wisdom of Crowds "explores a deceptively simple idea that has profound implications: large groups of people are smarter than an elite few, no matter how brilliant—better at solving problems, fostering innovation, coming to wise decisions, even predicting the future." Now this idea has been put into practice with Consensus View, a site where you can enter your predictions on stocks, commodities, and currencies, and view the group consensus. (from wsj.com)
posted by reverendX on Sep 18, 2005 - 46 comments