Before revision:  Here, we propose the concept of a significant tie to statistically evaluate the strength of a relationship . Application of the proposed method to the Italian interbank networks reveals that the percentage of relationship lending among all bilateral trades is consistently around 20\%-30\% and that their trading properties are distinct from those of transactional trades .
After revision:  Here, we propose the concept of a significant tie to statistically evaluate the strength of a relationship . Application of the proposed method to the Italian interbank networks reveals that the percentage of relationship lending among all bilateral trades has been quite stable and that the relationship lenders tend to impose high interest rates at the time of financial distress .