Codetermination did not lower German profits.

"When measured by EBIT(DA) over revenue, we find a reduction in the profit margin by about 5ppt. EBIT(DA) over total assets yields an order of magnitude smaller effects, insignificant in all 16 specifications. For net income, we find positive point estimates across specifications and normalizations. For net income over revenue, they are statistically significant (marginally in two of the four positive specification) between 0.07 and 0.11. We find estimates of around 0.02 (SE 0.015) for effects on net income over assets. Measured by the different profit outcomes we consider, the evidence does not suggest that shared governance lowers profits."