Data issues (huge spikes) on UK stocks.
A lot of your charts seem to have huge random spikes down and then up again. Here are some examples:
UK Stocks (daily or weekly charts):
AEMC.L, AAIF.L, AZN.L, BA.L, CPG.L, CRDA.L, ... and a lot more.
These can be verified by your team by looking at Yahoo stock CANDLE charts.
Kind Regards.

Hi,
Please provide specific examples of the data issues along with screenshots at finance.support@verizonmedia.com so we can further investigate this matter. Thank you!
Regards,
Yahoo Finance