No, they don&#x27;t.  In any panic, HFTs disappear like anyone else.  They are middlemen, not producers.  They insert themselves into the middle of trades to make profits for themselves.<p>If I put in a market order when the price is $100, and a HFT firm sees my order, beats me to market, buys up all the $100 offers and then resells the stock to me at $105, my liquidity hasn&#x27;t been improved in the slightest.  All that has happened is that someone has front-run my order and cost me $5&#x2F;share, extracting profits from my pocket without providing any useful service to anyone.<p>If you want this comment in more technical terms, here it is:<p><a href="http:&#x2F;&#x2F;www.zerohedge.com&#x2F;news&#x2F;2015-08-25&#x2F;cutting-through-hft-lies-what-really-happened-during-flash-crash-august-24-2015" rel="nofollow">http:&#x2F;&#x2F;www.zerohedge.com&#x2F;news&#x2F;2015-08-25&#x2F;cutting-through-hft...</a>