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Comment by binarybits | Hacker News Reader

I think there's something to this, and I say as much in my story. But with exchanges trading at different values, it's hard to know which price is the "real" one.

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They're all "real". Somebody, somewhere, traded that tick, fiat (or gox$) and bitcoin changed hands.

If you consider the 4 largest exchanges (together about 90% of the volume), then you can look at the price as this fuzzy zone somewhere between the highest and lowest tick.

If you want to know when a specific price has been surprassed comprehensively, it's when all of the top exchanges have gone over it (not just one).

But if you want to know if it's somewhat likely a specific price will be surpassed by all exchanges, then just one going over carries a lot of meaning.

Dollars that you can actually access are real, and ones that you can't access (e.g. in a MtGox account) are fake. A price denominated in fake dollars is a fake price.

It's true that Gox$ aren't US$. But that doesn't mean they're entirely fake.

The matter of the fact is that, some people are doing arbitrage between Gox and other exchanges. And this arbitrage keeps prices somewhat in line. If the arbitrage would not exist, then the prices would be all over the place and not correlate at all.

The question then is, if the Gox$ are all fake and nobody can get any, how come the arbitrageurs can keep in business? And the answer is: they couldn't. Some people get to convert their Gox$ to US$ and then use them to buy bitcoin on other exchanges to sell them on Gox.

But, not all people, for whatever reason, get to do that. And the process might be lengthy, and there's a risk that it might fail for you.

So the spread between Gox and other exchanges is the arbitrageurs estimate of the risk of selling BTC to Gox$ and be able to convert them in a suitable timeframe to US$.

The last thing I heard is that you can get money out quickly by paying a 5% fee, so I think you're right that arbitrage is keeping the price difference around 5%.

Doesn't this apply to anything you can buy from multiple places? Milk may be $1.50 from a corner shop but $2 from a supermarket. What price is the "real" one? Taking a mean average based on trade volume seems to be the most logical way to value it.

I guess as good becomes more liquid (like USD and gold) then the gap gets reduced.

I've never had any problems cashing out at MtGox, but I also trade in yen.

How long does it take to cash out in JPY ?

Given that is where Mt.Gox is located, I would not be surprised to hear <5 days.

I have heard this before, "Mt.Gox is not a bad company to do business with if you're in Japan." They are not a sham company by any means, they are just hamstrung by US government intervention.

My cash out time was like a day once support corrected an error on my part I had made when setting up my bank account.

Perhaps the Coindesk weighted index?

http://www.coindesk.com/price/

Among other factors, for inclusion in the index, money must be liquid within 7 days.

Also http://www.bitcoinaverage.com

They are all real. And yet they are all fake. One might guess the lowest markets price is the closest to the actual value, but you most look at the volume of trades. And, this is what I think is partly due to the major gaps between Gox and Bitstamp and other markets, is the ease/fees of the different markets and actually going from say USD to BTC and back again.

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