Table 6. Additional estimation result (dependent variable: annual R&D investment per stock)

Specification	GMM-SYS
Specification	Industry with lower zombie share	Industry with higher zombie share	Firms only that have ever experienced zombie status
λ1Ri,t−1Ci,t−2	–0.005^** (0.002)	–0.001^** (0.000)	–0.044 (0.029)
γ₂Δy_i,t	0.089^** (0.038)	0.068^* (0.035)	0.039 (0.039)
γ₂Δy_i,t-1	0.076 (0.049)	0.091^*** (0.034)	0.033 (0.034)
γ₄ (c_i,t-2 − y_i,t-2	–0.190^*** (0.038)	–0.179^*** (0.039)	–0.242^*** (0.057)
γ₂y_i,t-2	–0.102^*** (0.022)	–0.098^*** (0.031)	–0.162^*** (0.034)
ϕ1Zombie statusi,tCi,t−1	156,423.6^*** (59,056.56)	5,328.1^** (613.35)	4,874.8^** (886.46)
Constant	1.828^*** (0.372)	0.000^*** (0.000)	0.000^*** (0.000)
Firm fixed	Yes	Yes	Yes
Year fixed	Yes	Yes	Yes
Observations	1,014	1,967	971
R-squared	-	-	-
Number of firms	239	465	234
Number of instruments	21	21	21
F-statistic	18.58	309.60	159.57
P (F-statistic)	0.000	0.000	0.000
AR test (p-val) 1^st order	0.038	0.176	0.011
2^nd order	0.144	0.332	0.904
Hansen J test (p-val)	0.332	0.006	0.198

are statistical significance at 1%,
5%,
10% respectively; and standard errors are also reported in parentheses; p-values are reported for AR test and Hansen J test. R&D, research and development; GMM-SYS, Generalized Method of Moments System; AR, auto-regressive.