For these purposes, GMT (Greenwich Meridian Time) is just the older name of UTC (Universal Coordinated Time). 

Perhaps you meant some other timezone? 

Most of Western Europe (except England, Ireland, Portugal, perhaps a few others) is 1 hour ahead.

So 02:30 UTC = 02:30 GMT = 03:30 in Western Europe, except those countries.

As others have pointed out, "market cap" is not very meaningful for a "stock" whose price is entirely speculative and which has large hoards that were bought by minuscule prices.

If I start a StolfiCoin with 1 trillion pre-mined coins, and manage to sell ONE coin to a kid for ONE dollar, my market cap will immediately be 1 trillion dollars. 

A more useful measure (but wrong in the opposite sense) would be the amount invested: the sum, over every coin or fraction thereof, of the USD amount paid in the LAST transaction of that coin or fraction.  Satoshi's coins, fr example, would contribute zero to this sum.  For bitcoin, I suspect that this number will be well below 1 billion USD.

Another measure, would be: if all the current owners decided to auction all their bitcoins -- say, within the space of a month -- to the people who do not own any bitcoins now, how much money would they get,?

The question perhaps should be, why did it stop trading.

Stopping the trading of a stock is a blow to investors who bought it on the assumption that they coud sell it any time they wanted. 

Please correct me if I am wrong, but I suppose that the owners of a stock market have the right to stop and resume trading any stock, unless they are bound by contract to keep trading it or whatever.

On the other hand, the company's executives should NOT have that right -- once sold, the shares are no longer the firm's property.

I understand that N&B management ASKED Havelock to stop trading, alleging some unspecified "irregular trading", and Havelock agreed; but since Havelock had no further information, they resumed trading.

Investors who could have sold their shares earlier were prevented from doing so, and now have lost almost all their investment.  (Well, if not them, someone else would have lost their money, anyway.)

Perhaps management did that in order to hide the collapse for a few more days while looking for new investors.

In my understanding, it means that China is sleeping so the arbitragers caught up with it.

What about

d) The Central Bank looked at the proposal (unexperienced CEO unfamiliar with the Cypriot market, tiny capital, extremely volatile assets with no real backing, vague business plans, etc.) , concluded that it would end up badly for the customers, and did what their public mission required them to do.

The BTC-China open letter http://www.coindesk.com/btc-china-dismisses-pboc-fears-open-letter/ is not as reassuring as the title of Coindesk's article makes it to be.  They do NOT seem to believe that the bank closure rumor is false, on the contrary the overal tone of the letter is rather gloomy for the sort tem.  It even calls the November rally a "speculative bubble"...

That may explain why the price has not made much of a recovery after the letter came out (now ~2750 at Huobi, compared to ~3500 just before the Caixin leak).

On the other hand, if the price had continued to follow its "natural" down trend (that it followed most of the time from Mar/15 to Mar/30), it would be now ~2450 CNY.  Ditto if we consider the exponential decay from Jan/29 to Mar/01.

So the BTC-China letter may indeed have had a positive effect, lifting the price by ~300 CNY (~50 USD).

If bitcoins will be treated as goods in the US, will the sale of bitcoins by exchanges be subject to state sales tax?

True ... if CNY withdrawals are suspended without advance warning, and the client's yuans get trapped in the exchange account.

But if the clients will have some advance warning, as the Caixin rumor claimed, I supose that most of them would sell (maybe even panic sell) their coins to arbitrage traders or hoarders, and take the cash out before the deadline.

Moreover, if CNY withdrawals are suspended, arbitrage between the Chinese exchanges and the rest of the world may become impossible.  In that case, even if the price shoots up at the Chinese exchanges, it will drop somewhat on Western exchanges,  as they receive the Chinese coins but not the Chinese money.   

I can't see how a decline of bitcoin trading in China could lead to a price increase.  If the blocking of bank accounts turns out to be a false rumor, as Huobi's note suggests, then perhaps the price will recover in time to the 3000--3500 CNY range (500--570 USD), even if the 3rd party channels remain closed.  If the bank accounts are closed too, the price in Western exchanges can only go down.

Weird.

I was expecting that Huobi's note "no problem with banks" would cause a price surge today.

Was it all "spent" on yesterday's surge, that lifted the price from ~2500 CNY to ~2650?

Meanwhile, the Neo & Bee situation looks increasingly ugly: https://bitcointalk.org/index.php?topic=529946.msg6056805#msg6056805

Rats! There goes my "lesson":
 
I am defenseless now... 

Now the market is waiting for official confirmation that the China situation is still uncertain. 

Well, Huobi's note brings back the uncertainty to the "March 29" stage.

It seems indeed plausible that the banks and 3rd party payment processors that called the exchanges were reacting to the Caixin article, rather than a PBoC note.  

In my understanding, the 3rd party processors were clearly violating the spirit of the December decrees, even if indirectly (through those recharge cards, which I am still not clear on how they worked).  Thus the Caixin article may have been sufficient to scare them into strict compliance.

On the other hand, the banks should have been safe (again, in my understanding), as long as they treated the exchanges like any other corporate client: dealing only with CNY, without involving themselves with bitcoins in any way.  So, the bank(s) that reportedly called some exchanges may have been overreacting.

Or perhaps the PBoC note was real, and did extend to the banks; but the banks may have convinced the PBoC that what they were doing was OK (and very lucrative, of course).  In that case, the note would have reached no further than the bank headquarters, and the branch managers would not know about it

It is possible therefore that the price will climb up to near the level of Mar/27 in the coming days, although the remaining uncertainty must have some negative impact.

EDIT: And, of course, the loss of the 3rd party channels should have a large negative impact.

Indeed.

There may be fake volume in the Chinese exchanges, but I have yet to see little evidence of it.  Mr. Lee's tells how they could do it, but gives no evidence that they do.

I have yet to see evidence of fake volume at Huobi. There is lots of robot (or script-assisted) trade, and their clients apparently trade much more than Westerners, on much narrower margins; but that is expected since there are no trading fees.  (If your competitor gets 10x your sales by charging 1/10 of your price, calling his sales volume "fake" is just pathetic.)

There is a suspicious steady background traffic at OKCoin, and (last time I looked) many small trades at random places within the spread (instead of at the ends of the spread, as one would expect for a trade triggered by only one of the parties). That may account for 10-20%  of their volume perhaps.  Otherwise their trade looks similar to Huobi's. 

I have not looked at the other major exchanges in China.

My understanding is that arbitrage trading is usually triggered after any significant change in price at one exchange, such as caused by a sizable trade (and "significant" and "sizable"  should be rather small given the no-fee policy).  Thus one should expect significant trades to be followed by other significant trades within tens of seconds at most. 

Actually the only clearly fake trade I saw in China was a burst of 40,000 BTC robot-traded at BTC-China within a some months ago, which several people noticed and understood to be by runaway trading robot(s).   Mr. Lee did not mention that, did he?

On the other hand, there was always suspicion of fake trades in MtGOX.  Analysis of the leaked database may perhaps prove or disprove that.  Who can tell whether the other Western exchanges are not doing it too?

In fact, I suspect that half or more of the trade at the Western exchanges is merely arbitrage trading from China. If and when China stops trading, we will be able to verify that.   

Mr. Lee obviously needs to justify why his exchange should be considered an important player in the Chinese market when their volume is now usually less than 1/20 of Huobi's or OKCoin's.  Actually there are other perfectly good explanations for their decline.

Finally, Western bitcoin startups looking for investors and clients obviously do not want to admit that the price of bitcoin was -- and still is -- defined largely by the speculative Chinese market, which is completely unpredictable and closed to them.  Of course the thesis of "fake volume" is music to their ears, even if there is no evidence to support it.

This article (dated today) seems to doubt whether the PBoC bank blockade is real:
http://www.techweb.com.cn/internet/2014-04-03/2024364.shtml
However the Google translation is extra garbled
"Bitcoin central bank ban the actual situation is questionable transactions chaos spawned free services [...]"
and I cannot tell whether the reporter knows more than we do, or less.

Not a ban on bitcoin, but a ban on some channels that bitcoin traders and investors had been using to deposit and withdraw yuan from the exchanges.   This ban was leaked last week, and is being implemented now.  If the leak is correct, it should be fully in force by April 15.  The ban should drastically reduce trading in China, and has already prompted many Chinese traders to sell their coins, which is why the price dropped so much since Thursday.

My understanding is
* The December decree prohibited
** merchant and services from accepting bitcoin or quoting prices in bitcoin
** internet stores from selling bitcoins
** banks from handling bitcoins in any way
** 3rd party processors from feeding bitcoin exchanges directly

After some hesitation, the exchanges found that they could still use bank accounts for deposits and withdrawals, and apparently found a way to use 3rd party processors indiretly for deposits (perhaps the client uses tha 3rd party processor to charge some sort of debit card that he then uses to deposit at the exchange?).  Even BTC-China had started doing that.

These loopholes enabled the Chinese exchanges to survive and keep growing (but then, presumably, mostly for speculation) and the price to recover promptly from the crash bottom level (380$ momentarily on Bitstamp) to 800$.

The new PBoC note was apparently written around March 18, and sent to the banks and 3rd party processors (not to the exchanges) sometime around March 31.  Its exact text is not known yet, but the Caixin leak of last week seems to be correct: the note closes both loopholes, by prohibiting the use of bank accounts and 3rd party processors for client deposits and withdawals.  According to the article, all such activities should be blocked by April 15.

Some banks and 3rd party processors have called some of the exchanges, telling them that deposits through those channels must stop "immediately" and withdrawals will eventually be stopped too. 

Several exchanges still have not reported such calls, and some have reported the blocking of one kind of deposit channel, but not of the other.  However I see no reason to believe that some exchanges would be treated differently from the others.  In fact, the Caixin article claimed that the note listed explicitly all the main exchanges including Huobi and BTC-China.

It was pointed out by "a source close to the PBoC" that blocking the bank accounts is more complicated than stopping the 3rd party services, hence it is understandable that the banks are taking longer to act.

I suppose one can still take a valise full of banknotes to the exchange.  However the bank probably will not allow the cash to be deposited into the exchange's account.  So, if the exchange allows the arbitrager to buy coins with that cash, it may be unable to honor the withdrawals by the sellers.  Unless the sellers go in person to the exchange to collect the cash. 

Unless there is a way to use the chaos elephant somehow to do that.  Whatever. 

Actually two exchanges (BTC38 and FXBTC) reported receiving notices from their banks that deposits should be blocked.

This thread monitors SecondMarket's Bitcoin Investment Fund purchases:
https://bitcointalk.org/index.php?topic=337486.0
The fund is supposed to buy bitcoins only if and when other people choose to invest in them. (You buy 10 SMBIT shares, they buy 1 BTC for you and keep it safe. After some years they may allow you to liquidate: you return the shares, they sell 1 BTC for you and give you the money, minus fees.)