The latest data point for COST's PEG Ratio, recorded in Q2'26, stands at 35.79, indicating a significantly positive valuation multiple that suggests the stock may be undervalued relative to its earnings growth potential in this period. Over the timeframe from Q3'23 to Q2'26, the PEG Ratio exhibits high volatility with no clear overall trend, oscillating between extreme negative values (such as -134.74 in Q2'25, signaling potential overvaluation) and positive peaks (like 35.79 in Q2'26). Notable inflection points include a sharp recovery from -14.36 in Q3'24 to 4.71 in Q2'24, followed by erratic swings, including a brief stabilization around 1.06 in Q4'24 before plunging to -2.52 in Q1'25; this pattern underscores sensitivity to earnings revisions and market expectations for Costco's growth trajectory.