@Drew Pearson Thank you Drew! Your question gets to something that's harder than I expected, and I haven't yet solved it (for my long-term purposes). My long-term predisposition has always been to weight sectors/industries because I own stocks that defy single bucket classification. My first version simply retrieved sector/industry from Yahoo! Finance (https://github.com/ranaroussi/yfinance), which is free, but for each ticker only returns a single sector + industry. My second version delegated inference to Perplexity via its API (https://console.perplexity.ai/) which was surprisingly easy and good at inferring classification into GICS sub-industries (https://www.msci.com/indexes/index-resources/gics); i.e., using the GICS but rather trusting Perplexity to infer primary classification. For the third version, I paid for API access to https://www.dcsc.ai/ because their theory appeals to me: a company (ticker) returns a 2-column matrix for up to four levels (!) of sector granularity, where the columns are relevance and confidence; i.e., in theory, for each ticker, I'd get back a list of sectors easily sorted by relevance/confidence. On their site, their example is Apple (AAPL) returns sectors Computer Hardware (95%), Application Software (80%), Smartphones (80%), etc. I do not consider the math that summarizes a detailed "vector of assignments" to be a hurdle; e.g., on my first run of this version, I simply accepted the top 3 and standardized their scores to sum to 100%. But if the vector is basically accurate, I think there various fun way to process the sector vector. However, Claude discovered problems with their data. Amazing! I would have eventually noticed the problems, but Claude saw them immediately and even proposed workarounds. Amazing! But after a few hours of too many problems with the source, I quit this source (and asked for a refund. I recommended they ask Claude to check their data before going to market) ... although Claude was willing to keep going lol.