Title Pending 2266

This is an accepted article with a DOI pre-assigned that is not yet published.This study investigates a theoretically significant paradox: financial literacy (FL) effectively moderates the stock popularity → investment decision pathway (β = −0.209, t = 3.987, p < 0.001, f² = 0.066) but fails to moderate the herd behavior → investment decision pathway (β = −0.073, t = 1.171, p = 0.242, f² = 0.008). Drawing on 217 Generation Z investors in Indonesia, we apply a moderated serial mediation model via SmartPLS 4, complemented by Multi-Group Analysis (MGA), simple slope analysis, and conditional indirect effects analysis. Simple slope analysis reveals that at high FL (+1 SD), stock popularity becomes statistically non-significant (β = 0.067, p = 0.379) an 86.2% reduction while herd behavior remains strongly significant at both high FL (β = 0.348, p < 0.001) and low FL (β = 0.494, p < 0.001). MGA comparing high-literacy (n = 108) and low-literacy (n = 109) investors confirms that the PS → investment decision path differs fundamentally across groups (Δβ = −0.330, p = 0.003), whereas the HB → investment decision path is virtually identical (Δβ = −0.003, p = 0.974). The conditional indirect effect of the serial mediation path (PS → Emotional Biases → HB → Investment Decision) is weaker but still significant at high FL (β = 0.066, p = 0.005) compared to low FL (β = 0.094, p < 0.001). Framed through informational cascades theory, we interpret these findings as consistent with what we term a ‘financial literacy firewall’ that appears to disrupt pre-cascade information evaluation but does not appear to reverse post-cascade behavioral momentum. Common method variance appears unlikely to account for the results, based on full collinearity inner VIF (all < 1.5, well below the 3.3 threshold), though the single-source, cross-sectional design means causal interpretation should remain cautious. Theoretical contributions to cascade theory, dual-process theory, and behavioral finance, as well as practical implications for financial education design and digital platform regulation, are discussed.