How HLT's 2017-01-04 stock split ratio is calculated?

External question — Personal Finance Stack Exchange Author: Azmisov Original post: https://money.stackexchange.com/questions/144564 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I am trying to understand a discrepancy among a few stock split data sources. One such example is HLT's split on 2017-01-04 (see https://ir.hilton.com/spin-off-information ). On this date, HLT spun off into HLT, PK, and HGV. Investors received 0.2 PK and 0.1 HGV for each HLT. HLT then had a 1:3 reverse split to bring the trading price back up. The NASDAQ's splits calendar shows a 1:3 ratio, however Yahoo Finance and splithistory.com both list a 1000:2052 ratio instead. Seems this latter split is accounting for the spinoff somehow. How do they arrive at 1000:2052... is that some officially published number? I am unable to figure out how they got that. My attempts at reproducing that ratio: HLT closed 2017-01-03 at $27.39, and opened 2017-01-04 at $57.3. That's a 1:2.092004381 ratio, so doesn't quite line up. From this link it seems "when issued" tickers PK-WI and HGV-WI started trading ~21 days prior. My guess is NYSE took the closing prices for those on 2017-01-03 to calculate the split ratio to apply the morning of the 4th. E.g A ratio of 27.39 : 3*(27.39 - close(PK-WI) - close(HGV-WI)) . However, I can't find any historical data for those when-issued shares, so can't verify if that gives us 1000:2052. Just seems there would be some central, officially published split ratios that the exchange applied to magically update the price.

External answer — Personal Finance Stack Exchange Author: Richard at NorgateData Original post: https://money.stackexchange.com/a/144565 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. There is no central source for split ratios. NYSE doesn't actually calculate split ratios - that is up to each data vendor to determine based upon the corporate actions reported. Here's how Norgate Data does it under the hood: Ex-date for corporate action: 2017-01-04 Entitlement date or corporate action: 2017-01-03 HLT Closing price on entitlement date: 27.39 HLT Open price on ex-date: 57.3 HLT Open price on ex-date: 58 Spinoff action leg 1: Demerger of 0.1 Hilton Grand Vacations (HGV, was trading as HGV-WI on the day HGV on entitlement date: 25.58 Value of leg 1: 2.558 Spinoff action leg 2: Demerger of 0.2 Park Hotels & Resorts Inc (PK, was trading as PK-WI on the day) PK on entitlement date: 30.5 Value of leg 2: 6.10 Total value of spinoffs: 2.558 + 6.10 = 8.658 Spinoff dilution factor: (27.39-8.658)/27.39 = 0.6838992332968237 Reverse split 1:3 = factor: 3 Combined factor: 0.6838992332968237 * 3 = 2.051697699890471 That factor is then applied to all prices prior to the ex-date. Regarding the "when issued" prices and historical data, this is also up to the data vendor. Norgate Data prepends any "when issued" pricing data to a stock's history. Some vendors don't do this though. Best regards, Richard Dale Disclosure: I am a co-owner of Norgate Data.