Managing RIC Changes and Historical Security Matching
Summary
The document explains why matching Reuters Instrument Codes (RICs) to Compustat tickers across historical datasets can be unreliable. Ticker-like identifiers may differ for share classes, as illustrated by examples where Reuters and Compustat use different punctuation or letter suffixes. More broadly, security identifiers can change over time, so a match that works for one period may not remain valid across a long history.
The suggested workflow is to create a stable internal security identifier and map each data source’s identifiers to it, accounting for corporate actions and source-specific conventions. Text-based tickers and RICs can be useful for an initial match, but should be checked for gaps and ambiguous cases. The answer recommends considering identifiers such as SEDOL, ISIN, or CUSIP as additional matching evidence. It does not provide a definitive RIC change history or a universal mapping rule; the right security master depends partly on how corporate actions are handled.
Key ideas
- RICs and company tickers can change over time, complicating historical joins.
- Share-class conventions can make apparently similar ticker strings differ across vendors.
- A security master should map source identifiers to a stable internal security identifier.
- Text-based identifiers are useful starting points but need checks for gaps and ambiguity.
- Non-text identifiers such as SEDOL, ISIN, or CUSIP can provide additional matching evidence.
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Full text
# Do companies' Reuters Instrument Codes (RICs) change over time? # Do companies' Reuters Instrument Codes (RICs) change over time? I am merging two datasets: 1) One which includes Reuters US companies' RICs and the number of news linked to each company; 2) Compustat US, taking data from 1996 to 2018. I have few questions: - In order to merge them, I consider that Reuters RICs without the stock exchange (e.g. AAPL for Apple) correspond to Compustat Company Ticker, is this correct? Looking through the Reuters RICs of companies mentioned in news during 2019, I found three exceptions to this rule, one of them is Moog Inc, whose Reuters' RIC is MOOGa, while Compustat Ticker is MOOG.A. The other two cases are different in the same way (JWa - JW.A and BRKb - BRK.B). I would like to know whether this is actually true. - Do the Reuters RICs change over time? Are they re-used or are they uniquely assigned to firms from 1996? For example, if I find a company's RIC in 1996, is it sure that this RIC will be always attached to the same company and will not be assigned to another company in the following years? In case RICs actually change, is there a guide with all the changes (possibly a guide that does not require to login in any website)? Thanks! ## Answer by Chris (score 1) https://quant.stackexchange.com/a/45750 You've stumbled upon one of the fundamental challenges to working with historical equity data. The quick answers are that (1) yes, identifiers can and do change over time; (2) there isn't a clear/obvious/'right' method for mapping securities in creating a security master, at least in part due to differing treatment of corporate actions; (3) the general approach involves creating a single unique security identifier and then mapping various sources to it, after which you're able to move back and forth between sources using the unique ID. In your case, linking on RIC/ticker should be good enough, and it'll become clear soon enough where there are gaps that need to be accounted for. I'd also generally recommend using something non-text-based (eg, SEDOL, ISIN, CUSIP) as matching on text-based IDs can be a little tricky (as you'd noted accounting for different share classes of the same company).
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