The study investigates short-term market adjustments following the introduction of price transparency requirements in Poland’s primary housing sector. Using a dataset of 57,041 dwellings across 23 cities and focusing on six major agglomerations, it analyzes how developers modified list prices and reporting practices during the 2025 rollout period. Results indicate that developers visibly repriced a large share of their inventories around key implementation dates, with the most pronounced activity in September 2025. In large urban markets, the adjustments were predominantly downward, reflecting strategic repositioning in anticipation of easier cross-project comparisons rather than shifts in demand fundamentals. These repricing waves temporarily reduced average list prices, creating misleading signals for less experienced market participants. The analysis also highlights the persistence of data inconsistencies and definitional ambiguities that limit comparability across projects. Despite greater public access to pricing information, uneven data quality continues to constrain accurate monitoring and interpretation of market dynamics. Consumers benefited from faster access to headline prices, yet analysts and smaller developers remained exposed to information gaps. Overall, the findings suggest that while transparency can promote more informed market behaviour, its effectiveness depends on robust data standards, auditability mechanisms, and the integration of verified transaction-level evidence.