Uniqueness of Ticker Symbols

[Martin Thomson]

After the study of

Translating Ticker Talk
Ticker symbol - Wikipedia, the free encyclopedia

I summarize the following about ticker symbols (please correct me, where I am wrong):

Ticker symbols are unique (mathematical unique) for one stock exchange at one point of time.
Ticker symbols may change over time. Old ticker symbols of delisted companies can be taken over by other companies at the exchange. The wikipedia article mentions the takeover of the ticker symbol V by Visa Card from the delisted Vivendi for instance.

Questions:
1. Are the ticker symbols of the NASDAQ and the NYSE all together unique at the moment, without referring the stock eschange?
2. Is there a list of ticker symbol changes, which is always updated?

 

[Yike Lu]

I'm not able to directly answer your questions, but I know that in practice, equity shops have to maintain their own unique security IDs internally and that this is a non-trivial task which includes looking over Corporate Actions (CAX) daily.

 

[pingu]

After the study of

Translating Ticker Talk
Ticker symbol - Wikipedia, the free encyclopedia

I summarize the following about ticker symbols (please correct me, where I am wrong):

Ticker symbols are unique (mathematical unique) for one stock exchange at one point of time.
Ticker symbols may change over time. Old ticker symbols of delisted companies can be taken over by other companies at the exchange. The wikipedia article mentions the takeover of the ticker symbol V by Visa Card from the delisted Vivendi for instance.

Questions:
1. Are the ticker symbols of the NASDAQ and the NYSE all together unique at the moment, without referring the stock eschange?
2. Is there a list of ticker symbol changes, which is always updated?

1. NO
2. NO

 

[MaxMaurice]

For #2-
You can look up ticker changes in a Bloomberg terminal.

Search CACT to look up corporate actions. This will NOT be an all-encompassing list of all ticker changes ever.

 

[Martin Thomson]

But

Ticker symbols are unique (mathematical unique) for one stock exchange at one point of time.

is true, right?

And the notation of the ticker symbol together with stock exchange differs from data provider to data provider? E.g. AAPL.NYSE may be AAPL.NY or AAPL.NYSTE at different data providers, right?

Are there ISIN Codes available for every US stock?

Martin