On October 15, prices of US government bonds – one of the most liquid markets in the world – whipsawed violently and sparked a wave of speculation on Wall Street as to the culprit(s) behind the wild moves.

Here’s a longish analysis of what happened. The key suspects: lack of liquidity, the rise of electronic trading, a classic gamma trap (possibly sparked by the scuppering of the AbbVie/Shire deal) and much, much more.

… On October 15, the yield on the benchmark 10-year US government bond, which moves inversely to price, plunged 33 basis points to 1.86 per cent before rising to settle at 2.13 per cent. While that may not seem like much, analysts say the move was seven standard deviations away from its intraday norm – meaning it might be expected to occur once every 1.6bn years.

For several minutes, Wall Street stood still as traders watched their screens in disbelief. Electronic pricing machines, which now play a bigger role than ever in the trading of Treasuries, were halted and orders cancelled by nervous dealers as prices see-sawed.

The events have sparked a financial “whodunnit” as investors, traders and regulators seek to understand what happened – and to determine whether October 15 was a unique event or a harbinger of further perilous trading conditions to come.

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Bonds: Anatomy of a market meltdown