……There are two rather more predatory strategies. One is called algo-sniffing. Here, a super-fast computer tries to find other computers going about their everyday business of buying or selling shares, and figures out what they’re going to do and when.
The algo-sniffer can then get ahead of the game and exploit the slower computer. And of course you could have algo-sniffer-sniffers and algo-sniffer-sniffer-sniffers in a high-frequency arms race. No wonder speed can be so important.
And finally, a particular sub-category of the algo-sniffer is the spoofer, which deliberately makes fake offers designed to lure other computers to show their hands, then cancels the offers. Spoofing might be illegal, or at least against the rules of stock exchanges, but it’s hard to prove that it’s going on.
Andrew Haldane, executive director for financial stability at the Bank of England:
“What we have out there now is this complex array of multiple mutating interacting machines, algorithms. It’s constantly developing and travelling at ever higher velocities. And it’s just difficult to know what will pop out next. And that’s not an accident waiting to happen, that’s an accident that has been happening with increasing frequency over the last few years.”
via BBC News – High-frequency trading and the $440m mistake.

Colin Twiggs is a former investment banker with almost 40 years of experience in financial markets. He co-founded Incredible Charts and writes the popular Trading Diary and Patient Investor newsletters.
Using a top-down approach, Colin identifies key macro trends in the global economy before evaluating selected opportunities using a combination of fundamental and technical analysis.
Focusing on interest rates and financial market liquidity as primary drivers of the economic cycle, he warned of the 2008/2009 and 2020 bear markets well ahead of actual events.
He founded PVT Capital (AFSL No. 546090) in May 2023, which offers investment strategy and advice to wholesale clients.