Hello Chakra Pip, and welcome to this forum.
To simplify things, take New York time (EST in winter, and EDT in summer) out of the conversation. You are looking at Tokyo and London, and you’re trying to figure out whether there is an overlap between those two sessions — so, New York doesn’t have anything to do with it.
Also, don’t assume that London time is GMT — that’s only true during northern hemisphere winter.
All that being said, let’s walk through it.
Tokyo is GMT+9 year-round (no daylight saving time). In the winter, London is GMT. So, the Tokyo close (at 5pm Tokyo time) occurs at 8am London time (9 hours earlier), just at the start of the London Session. So, technically, [B]there is no overlap between Tokyo and London in the winter.[/B] However, see the comments below about these so-called “opening” and “closing” times.
In the summer, Tokyo is still GMT+9, but London goes onto daylight saving time, which they call British Summer Time. BST=GMT+1, so the time difference between Tokyo and London in the summer is 8 hours, instead of 9 hours. This means that when London opens at 8am London time, it’s 4pm in Tokyo, and [B]there is a 1-hour overlap between the two sessions — that is, from 8am-9am London time, and from 4pm-5pm Tokyo time, both sessions are open, in the summer.[/B]
About the “opening” and “closing” times:
All over the world, from 8am Monday morning in New Zealand until 5pm Friday afternoon in New York, the retail forex market is open. In every country, 24-hours per day, for 120 hours per week, retail brokers are open for business, and retail traders can trade. But, the retail forex market is less than 3½% of total worldwide foreign exchange trading — so, it really doesn’t matter to the overall market what we little traders do.
For the players who matter in the foreign exchange market — central banks, top-tier investment banks, multi-national corporations, the largest hedge funds, etc. — the market never closes. But, their activity (forex trading volume) is concentrated in the so-called “normal business hours” of their respective locations. So, trading volume is much higher during the daytime than it is at night, in every city, country, or so-called “session”.
When we talk about the market “opening” in Tokyo, or London, or anywhere else, we’re simply saying that the normal business day is starting, and forex trading volume is ramping up, along with every other form of business activity.
The “normal business day” is not exactly 8am-5pm everywhere in the world, but those times are a reasonable average, and most of each country’s foreign exchange trading volume occurs during that time period. I have studied forex volume patterns quite extensively, and my estimate is that about 83% of total daily transaction volume occurs during the 9 hours between 8am and 5pm, in every forex market. The other 17% is spread across the 15 hours between 5pm and 8am.
So, we should not think of the forex market in any location as something like a stock exchange, where a bell rings at 8am to start the trading day, and then rings again at 5pm to halt all trading. Rather, think of the forex market more like the real estate market. Is most real estate bought and sold during “normal business hours”? Probably. But, I once sold a house at midnight. And, I’ll bet that real estate has been bought and sold at 2am, and 5am, and any other time you care to mention.
When does the forex market “close” in Tokyo? — Probably at about the same time that the real estate market “closes” in Tokyo.
About errors in the Babypips School lesson on session times:
I told wandez that I would contact Pipstradamus about the error which he found in the lesson. I’ll re-read the whole thing, and look for the misprint you referred to. Maybe we can get the whole lesson cleaned up once and for all.
There’s no doubt that a worldwide market, spanning 27 time zones, tends to be confusing. Throw daylight saving time into the mix, with different countries going onto or off of DST at different times of year, and you have a bigger mess.
But, if we all work together, I think we can keep the mess untangled.
Edit: I have posted to Pipstradamus (in the Bugs and Suggestions forum) regarding the misprint you found, as well as the error which wandez found. Give it a few days — then, that page in the School should be fixed for good.
Here’s a link to my post to Pipstradamus — 301 Moved Permanently