In a new report, global banking regulators report that the variation in the calculation of banks’ risk-weighted assets for capital purposes increases with more complex trading positions.

The Basel Committee on Banking Supervision published its second report on the consistency of risk-weighted assets (RWAs) for market risk in the trading book today. The first report, which was released back in January, found significant variation in the calculation of RWAs, and the resulting capital requirements. The committee says that its latest research confirms that finding, and reveals that the variation increases with the complexity of trading positions. It says its analysis also re-confirms the finding that differences in modeling choices are a significant driver of variation in market risk RWAs across banks.

The report reiterates the Basel Committee’s original policy recommendations, which call for: improving public disclosure and the collection of regulatory data; narrowing the range of modelling choices for banks; and, further harmonising supervisory practices for approving capital models.

The regulators note that they have since proposed a series of measures designed to narrow market risk variability. They are also developing proposals to improve disclosure requirements for banks that will aim to “significantly enhance the quality, content and consistency of disclosures related to market risk RWAs.”

“Today’s report complements and reinforces the committee’s earlier trading book report. It shows that, as portfolios get more complex, the variability can increase. These findings, along with the results of the committee’s banking book review, have been important inputs to our ongoing work to address RWA variations,” said Stefan Ingves, chairman of the Basel Committee and governor of Sveriges Riksbank.