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I was wondering which website or service is the main source of the prices of some shares/stocks. Because I heard that google has a delay of 15 minutes with showing the results of a stock/share.

Is there a official website where the results are posted first? I am new into the "trading stuff", so correct me if I said something wrong.

Thanks in advange!

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The main source is a direct feed from the stock market itself. The faster the feed, the more expensive. 15-minute delay is essentially free... and for those of us who do long-term investment is more than adequate.

If you want data sooner, sign up with a brokerage that provides that service as part of what you're paying them for... and remember that every bit you spend on services is that much more profit you have to make just to break even, so there's a real tradeoff.

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To expand on keshlam's answer:

A direct feed does not involve a website of any kind. Each exchange publishes its order/trade feed(s) onto a packet network where subscribers have machines listening and reacting.

Let's call the moment when a trade occurs inside an exchange's matching engine "T0". An exchange then publishes the specifics of that trade as above, and the moment when that information is first available to subscribers is T1. In some cases, T1 - T0 is a few microseconds; in other (notorious) cases, it can be as much as 100 milliseconds (100,000x longer).

Because it's expensive for a subscriber to run a machine on each exchange's network -- and also because it requires a team of engineers devoted to understanding each exchange's individual publication protocols -- it seems unlikely that Google pays for direct access. Instead Google most likely pays another company who is a subscriber on each exchange around the world (let's say Reuters) to forward their incoming information to Google. Reuters then charges Google and other customers according to how fast the customer wants the forwarded information. Reuters has to parse the info it gets at T1, check it for errors, and translate it into a format that Google (and other customers) can understand. Let's say they finish all that work and put their new packets on the internet at time T2.

Then the slow crawl across the internet begins. Some 5-100 milliseconds later your website of choice gets its pre-processed data at time T3. Even though it's preprocessed, your favorite website has to unpack the data, store it in some sort of database, and push it onto their website at time T4.

A sophisticated website might then force a refresh of your browser at time T4 to show you the new information. But this forced refresh involves yet another slow crawl across the internet from where your website is based to your home computer, competing with your neighbor's 24/7 Netflix stream, etc. Then your browser (with its 83 plugins and banner ads everywhere) has to refresh, and you finally see the update at T5.

So, a thousand factors come into play, but even assuming that Google is doing the most expensive and labor-intensive thing it can and that all the networks between you and Google and the exchange are as short as they can be, you're not going to hear about a trade -- even a massive, market-moving trade -- for anywhere from 500 milliseconds to 5 seconds after T0. And in a more realistic world that time will be 10-30 seconds.

This is what Google calls "Realtime" on that disclaimer page, because they feel they're getting that info to you as fast as they possibly can (for free).

Meanwhile, the computers that actually subscribe to an exchange heard about the trade way back at time T1 and acted on that information in a few microseconds. That's almost certainly before T2 and definitely way way before T3. The market for a particular instrument could change direction 5 times before Google even shows the first trade.

So if you want true realtime access, you must subscribe to the exchange feed or, as keshlam suggests, sign up with a broker that provides its own optimized market feeds to you.

(Note: This is not an endorsement of trading through brokers.)

  • Agreed, not an endorsement of brokers -- or, for me at least, of doing any kind of trading where the difference between milliseconds and a day matters a lot. – keshlam Jun 30 '15 at 0:08

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