Moderating influence of product diversification on the international diversification-performance relationship: A meta-analysis

•The relationship between international diversification and firm performance has an inverted U-shape.•Firm performance is higher in firms with low/related product diversity and lower in firms with high/unrelated product diversity.•Reverse causality exists between international diversification and product diversification such that performance is marginally higher for firms pursuing a dual international-product diversification strategy.•Firm performance is higher among firms with higher R&D and advertising intensity.•Firms from advanced and emerging economies display identical internationalisation levels.