Update equities.csv

[CarbonFixer]

1. remove many tickers that no longer exist
2. add some missing tickers
3. fix a couple of wrong company names

[JerBouma]

Hi! Thanks for this, how did you verify that all 18k records removed no longer exist? Its good to note I'd rather add a tag that the company ceased to exist than remove it altogether. Also given that sometimes via other sources you can still obtain data of delisted companies.

[CarbonFixer]

@JerBouma this was through checking against yahoo finance and noting all cases where the response was that the ticker does not exist.

[JerBouma]

Just because Yahoo Finance no longer has any data on the instrument doesn't justify the removal given that different sources could still have data on these tickers. This can be for example delisted companies.

If we remove all items where one source has no data, we create a survivorship biased dataset.

Happy to merge if you can instead add a delisted column and pass the boolean True for all instruments that match your criteria!