No. This is just one of several places where the laws systematically favor the bulls.

Believe this is not a "law" but a "policy" Regardless, your sentiment is spot-on.

Its an enforcement policy directed by the SEC. Its effectively a law, you can’t opt out for instance.

Well, you can choose not to follow laws (but you'll face the consequences if caught!).

You are wrong about that. See T5, T6, and H10 halts.

T5: Single Stock Trading Pause in Effect Trading has been paused by NASDAQ due to a 10% or more price move in the security in a five-minute period.

T6: Halt - Extraordinary Market Activity Trading is halted when extraordinary market activity in the security is occurring; NASDAQ determines that such extraordinary market activity is likely to have a material effect on the market for that security; and 1) NASDAQ believes that such extraordinary market activity is caused by the misuse or malfunction of an electronic quotation, communication, reporting or execution system operated by or linked to NASDAQ; or 2) after consultation with either a national securities exchange trading the security on an unlisted trading privileges basis or a non-NASDAQ FINRA facility trading the security, NASDAQ believes such extraordinary market activity is caused by the misuse or malfunction of an electronic quotation, communication, reporting or execution system operated by or linked to such national securities exchange or non- NASDAQ FINRA facility.

H10: Halt - SEC Trading Suspension The Securities and Exchange Commission has suspended trading in this stock.

Those seem to me be to be directed more at price manipulation of individual stocks (eg pump and dump schemes) than restraining enthusiasm across the whole market. I'm open to correction on this (and will not demand a halt).

Because my google-fu is so bad ... has a major exchange ever actually stopped trading because it gained too much?

The T5/T6 are not really directional circuit breakers though. They are momentum breakers that don’t bias towards downward momentum.

I don't know if that's a good way to look at it. It's not just "bears" selling when you have a big drop. It's people who need the money for something and are worried about liquidity.

Trading halts may or may not fix that, but that's their purpose.

> It's people who need the money for something and are worried about liquidity.

Then they're doing it wrong. You shouldn't have money that you need immediately in the stock market. Yes, people will do that anyway, but I'm not sure we should cater to those people when the health of the markets as a whole are at stake (assuming circuit breakers are effective; up for debate).

Because bulls and bears aren’t equal. The laws should be favored towards not destroying the economy needlessly.

Because extremely bull markets are a strong indicator of a bubble the laws should be equal to prevent bubble bubble bubbling.

Are they? The market reaches all time highs almost every year, so would you say that we spend most of our time in bubbles?

It is actually expected that the market will typically go up, not down. Otherwise there would be no difference between investing and gambling.

It's a question of velocity - markets go up and down all the time... but speed breaks to prevent the market from going down to fast also need to prevent the reverse case - some sudden inexplicable and extreme price spiking.

Basically - we should protect against any really dramatic sudden changes as chances are that something is wrong.

In the last year the S&P grew ~22% prior to this recent drop, that's fine... and on a day swings in the low single digits might be fine. But if we woke up tomorrow and the S&P had recovered the pre-drop value and then grown 20% over that price - something weird is clearly going on and we should be worried.

This isn’t the economy

You can easily sell a market to zero, however it is much harder to buy a market to infinity.

* It's very difficult to sell a market to zero, but impossible to buy it to infinity.

Has any stock or financial instrument ever been valued at infinity? I don't know enough about finance to rule that out and it seems unlikely but at least possible.

For instance here is a toy example of unbounded value: Consider a market for a stock in which the only market participants are two bots with the behavior that they trade the stock back and forth at an asymptotically increasing price. The buys are backed by loans from a zero interest government bank. Since the bank is efficiently hedged to losses. Both sides of the trade owe the bank, the seller can also pay the bank the money the bank needs to back the buyers loan. Thus, the bank could allow both these loans to go to infinity causing the value of the asset to approach infinity.

Similar things have happened with flash loans in the cryptocurrency space.

At what point does a finite increase of the price turn it from a finite number into infinity?

No. Money is a scarce resource and modern algorithmic trading has limits to prevent another LTCM.

What is the price of a share that isn't listed for sale?

Emptying out all the asks is a thing that happens.

Why would you need them?