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Comment by dnadig | Hacker News Reader

The single stock circuit breakers were put into effect after the 2010 "flash crash" and they're designed to "let cooler heads prevail" when stocks or ETFs go wonky. The problem is that in a real panicky freefall, it just makes the window where the stock is trading very very small (it halts for 5 minutes, opens, hits the next breaker, halts for another 5 minutes, etc.)

It happens both up AND down. This last monday was really the first time they'd been tested en mass.

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I don't see that as a problem. The circuit breaker size is 10% (5% in some markets, I believe) for 5 minutes. It would take less than 2 hours to completely obliterate a single ticker, and each market participant gets the "same" amount of play time as before.

It might slightly favor HFTs if things do change across those 5 minute downtimes. Otherwise, your orders should be just as valid before the freeze as after, no?

Who cares if stocks flash crash? If you're buying stock for short term profit you deserve to be screwed by volatility and I have no sympathy for you.

>If you're buying stock for short term profit you deserve to be screwed by volatility and I have no sympathy for you

These people increase market liquidity, they too serve a purpose. If only long term investors were in the market, the exchanges would end up looking like ebay.

Why would that be a bad thing? (honest question)

Because most people have things they'd rather do than playing trader when their expertise is in something else. Being able to trade in and out of assets at a fair price at any time is valuable. Would you rather have your net worth tied up in a liquid index ETF or illiquid startup equity?

If I need the cash more than a few years out, whichever provides the highest return, like all long term investments.

What if you have a stop loss order?

why not use a stop limit order? It's kind of like setting a reserve price on ebay -- sell if you want to get out of a particular position, but not if the price gets to be too low.

In a little more detail:

A 'stop loss' order will sell once the share price falls below a threshold. It will sell using a market order, meaning whatever the current best price might be.

A 'stop limit' order will sell once the share prices falls below a threshold too, but will sell using a limit order, setting a minimum price that you're prepared to be paid.

In a crashing market, stop loss orders can result in you selling stocks for pennies, regardless of their rational worth. Stop limit orders protect you from excessive price drops.

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