We reassess the recent finding that no established portfolio strategy outperforms the naively diversified portfolio, 1/N, by developing a constrained minimum-variance portfolio strategy on a shrinkage theory based framework. Our results show that our constrained minimum-variance portfolio yields significantly lower out-of-sample variances than many established minimum-variance portfolio strategies. Further, we observe that our portfolio strategy achieves higher Sharpe ratios than 1/N, amounting to an average Sharpe ratio increase of 32.5% across our six empirical datasets. We find that our constrained minimum-variance strategy is the only strategy that achieves the goal of improving the Sharpe ratio of 1/N consistently and significantly. At the same time, our developed portfolio strategy achieves a comparatively low turnover and exhibits no excessive short interest.

We investigate whether and how financial constraints of private firms depend on bank lending behavior. Bank lending behavior, especially its scale, scope and timing, is largely driven by bank business models which differ between privately owned and state-owned banks. Using a unique dataset on private small and medium-sized enterprises (SMEs) we find that an increase in relative borrowings from local state-owned banks significantly reduces firms’ financial constraints, while there is no such effect for privately owned banks. Improved credit availability and private information production are the main channels that explain our result. We also show that the lending behavior of local state-owned banks can be sustainable because it is less cyclical and neither leads to more risk taking nor underperformance.