This study tests the Stock Internal Rate of Return Including Price Appreciation (SIRRIPA), derived from the Potential Payback Period (PPP) framework, as both a standardized stress-test and a predictive return metric. For 50 U.S. technology stocks (Sept 5–Nov 3 2025), SIRRIPA correlates positively with subsequent performance (r = 0.26; p = 0.07; ρ = 0.92; p < 0.001), with a 30-point spread between top and bottom deciles. Parallel global research reports r ≈ 0.76–0.82 between PPP-based yields (SIRR/SRP) and realized market returns measured over longer horizons of up to two years. Together, these findings confirm that standardized, yield-based valuation metrics consistently link intrinsic fundamentals to realized performance across both firm and market scales.