ETF Price Puzzles Solved: Tiingo Updates Adjusted Prices for TQQQ and Beyond This blog post is a follow-up to an earlier one (published November 30, 2025) titled “ ETF Price Puzzles: Examples Showing Tiingo’s Raw and Adjusted Series Don’t Always Differ ”. That prior post reported that adjusted prices from Tiingo for the TQQQ ticker did not follow the expected pattern for a 2-for-1 stock split on 2014-01-24. As a result, the prior post developed and demonstrated a T-SQL script for calculating custom adjusted price values based on Tiingo raw prices and stock-split ratios. Several days before publishing the prior post on November 30, 2025, I alerted Tiingo about the aberrant adjusted close values. This gave Tiingo an opportunity to correct the issue for future downloads from the Tiingo site by other analysts and stock traders. This post, which is published 2 to 3 weeks after the earlier post, expands the scope of the examination to cover more tickers and more stock...