[claude]

Requested by Houtan · Slack thread

Before: The nightly yfinance fetch (2026-11-01) flagged PSKY as an uncurated ticker: it returns no data and is no longer in the S&P 500 list. It is in neither nullified_questions nor ticker_renames. Each night it gets carried forward as resolved and triggers the Slack alert. Its resolution file also stops getting new prices, so the PSKY pair questions in the pool would resolve to stale prices.

After: PSKY maps to SKYD in yfinance ticker_renames. The fetch no longer requests PSKY and fetches SKYD instead. The updater writes SKYD's history to PSKY's resolution file, so existing PSKY questions and pairs resolve on live prices and the alert stops. test_known_renames_present now also asserts PSKY -> SKYD.

How: this is a rename, not a delisting. When Paramount Skydance's acquisition of Warner Bros. Discovery closed on 2026-10-06, the company changed its name to Skydance Corporation. Its Class B stock moved from Nasdaq (PSKY) to the NYSE under the new symbol SKYD. The security and its holders stayed the same; only the symbol changed. (The cash-out delisting was WBD's, handled in #341.) Sources:

• Paramount Skydance 8-K (2026-10-02), announcing the ticker change from PSKY to SKYD with the NYSE listing on 2026-10-06, and the name change to Skydance Corporation: https://www.sec.gov/Archives/edgar/data/0002041610/000110465926113076/tm2626659d3_8k.htm
• TradingView News, "Skydance to list Class B shares and warrants on NYSE; ticker to change to SKYD": https://www.tradingview.com/news/tradingview:01ced82c4b7be:0-skydance-to-list-class-b-shares-and-warrants-on-nyse-ticker-to-change-to-skyd/
• Cord Cutters News on the deal closing and SKYD trading on the NYSE: ''https://cordcuttersnews.com/its-done-paramount-completes-warner-bros-discovery-acquisition-launches-combined-company-as-skydance''/

Caveats for the reviewer:

• I could not re-run the yfinance fetch for PSKY or SKYD from the sandbox, because its egress proxy blocks the Yahoo Finance hosts (403 on CONNECT). I also could not check that Yahoo serves pre-2026-10-06 PSKY history under SKYD. Please confirm that yf.Ticker("SKYD").history(period="max") goes back to Aug 2025 before merging.
• On 2026-10-13, SKYD distributed warrants (SKYD WS) to Class B holders. Yahoo may adjust historical closes for that distribution.
• Possible follow-up, not in this PR: the pair pool in src/sources/yfinance_questions.py still lists PSKY. With the rename, those pairs drop out of sampling but keep resolving. Regenerating the pool would pick up SKYD if wanted.

Tests: ruff check and ruff format --check are clean on the touched files. pytest on src/tests/unit/sources/test_yfinance.py, test_yfinance_pairs.py, src/tests/unit/scripts/test_generate_yfinance_pairs.py and src/tests/unit/test_base_source.py gives 154 passed. The full suite needs Python 3.14 syntax, which the sandbox cannot install.

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