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For example, look up the London Stock Exchange stock CloudBuy PLC (CBUY) -
The closing price on 7th June 2017 is different among data providers -
1) Google search the ticker and evaluate the price on chart: 2.88GBX
2) London Stock Exchange - search stock on website: 3.75GBX
Anyone got any clues as to why there are these inconsistencies because I'm stumped.
Although the London Stock Exchange is an exchange we don't cover in our services, when we were researching this exchange for coverage viability several years back we observed some interesting points that are relevant to this question. At that time, we purchased/subscribed to several vendors' data.
Multiple platforms on one exchange
The separate trading platforms used by the London Stock Exchange each had different price reporting. For example, the electronic order book-based platforms reported actual trades in the daily OHLC summaries but the market-maker-based platforms were reporting midpoint of the bid/ask. Where a stock traded on multiple platforms there were significant discrepancies in the OHLC.
The following comments relate to data discrepancies in general:
Trades/Quotes
It is important that you know exactly what the open, high, low, close and volume represent. i.e. which trades (or quotes) are used, what time periods are used and which condition code(s) are excluded/incorporated. - e.g. consider the effect of block trades, multi-leg trades, cancelled/busted trades etc.
Multi-exchange trading With cross-border/cross-exchange trading also available for some securities, if you are looking at consolidated/combined trading feeds, you need to determine which rules are in place for such trades too.
Historical data adjustments Historical data can be adjusted for various corporate events such as stock splits, spin-offs (de-mergers), stock dividends, special dividends, special distributions, capital distributions, normal dividends, distributions in a currency other than the trading currency, events that give the holder a choice of multiple options etc. There are often different interpretations for the surviving entity of spin-offs/de-mergers too.
Errors
Lastly, it may just be data error(s) made by the data supplier (e.g. corporate actions that have subsequently been changed/cancelled)
Summary
Discrepancies are commonplace. Ask your provider how they handle all of the above if it is not documented.
You certainly ask the right question ... "got any clues". Yes, some clues are that free market data has no warranties but more importantly CBUY has low volume so that could be a reason.
There's one strange thing on https://finance.google.com/finance?q=cbuy where the chart x axis shows Wed Jun 7 2017. But when hovering over the close of that day, the upper left date shows April 17, 2018 15:30 Price 3.90.
When I move the slider a bit to the left with a month view, the dates are daily but moving it slightly to the right gives 'intraday' bars.
Could be just a data problem with CBUY on Google.
This sites shows 3.76 ... https://www.tradingview.com/chart/?symbol=LSE:CBUY
A lot of the historic data is adjusted for stock splits. Some sites also adjust the data for dividends. This can cause different prices on different sites.
