Leverage Ratio

The Leverage Ratio, in the Basel III regulatory sense, compares a bank's core capital to its total exposure, including on-balance-sheet assets and certain off-balance-sheet items, without adjusting that exposure for how risky it is. It is a deliberately blunt backstop against excessive borrowing: where Risk-Weighted Assets (RWA)-based capital rules reward banks for holding assets that models judge "safe," the leverage ratio treats a dollar of government bonds and a dollar of risky loans the same, so a bank cannot lean entirely on favorable risk weights to grow its balance sheet without adding real capital.

This regulatory leverage ratio is distinct from the general concept of Leverage used across corporate finance and investing. The Basel version was added after the 2008 crisis showed that several large banks had passed risk-weighted capital tests comfortably while running enormous, barely-capitalized balance sheets, and it was finalized by the Basel Committee on Banking Supervision (BCBS) as part of the broader Basel III package.

Imagine two shopkeepers who both say they are "well capitalized" because their inventory is insured against theft and fire. One shopkeeper has a small, cheap shop; the other has borrowed heavily to fill a giant warehouse with inventory, insured the same way. A risk model focused only on insurance quality might rate both as equally safe. A simple rule that instead asks "how much is your own money versus how much is borrowed, regardless of what you did with it" catches the warehouse operator's bigger exposure immediately. That is what the leverage ratio does for banks: it ignores the clever risk-weighting arguments and just measures capital against raw size.

Because it ignores risk weighting entirely, the leverage ratio acts as a floor underneath the more sophisticated capital rules, catching cases where a bank's models say its assets are safer than regulators are comfortable assuming.

The ratio is defined as:

• $\text{Tier 1 Capital}$ is a bank's core going-concern capital, chiefly common equity and retained earnings, as defined under Regulatory Capital rules.
• $\text{Total Exposure Measure}$ is total on-balance-sheet assets plus specified off-balance-sheet items such as undrawn credit commitments and derivative exposures, with no risk weighting applied.

If a bank holds $60 billion of Tier 1 capital against a total exposure measure of $1,200 billion, its leverage ratio is $60 / 1{,}200 = 0.05$, or 5%. Regulators set a minimum leverage ratio that banks must meet regardless of how low their risk-weighted assets appear, with additional buffers often applied to the largest, most systemically important institutions.

The ratio moves with two things: how much Tier 1 capital a bank holds, and how large its total balance sheet and off-balance-sheet commitments are. A bank that grows rapidly by taking on low-risk-weighted assets, such as sovereign bonds or mortgages, can see its risk-weighted capital ratios stay comfortable while its leverage ratio tightens, because the leverage measure does not give those assets any credit for being "safe."

Central bank balance-sheet operations interact with the leverage ratio in a direct way: when a Central Banks expands reserves through quantitative easing, those reserves sit as low-risk but non-zero exposure on bank balance sheets, and a binding leverage ratio can discourage banks from absorbing them, which is why several jurisdictions have temporarily excluded central bank reserves from the exposure measure during periods of balance-sheet expansion.

Minimum leverage ratios set by regulators tend to be low single-digit percentages, reflecting that the measure is a backstop rather than the primary capital constraint for most banks. Global systemically important banks typically carry additional leverage buffers on top of the baseline minimum, and well-capitalized large banks generally report ratios above their applicable minimum with some margin to spare.

Because it ignores risk entirely, the leverage ratio can discourage banks from holding very safe, low-margin assets such as government bonds and central bank reserves, since those assets consume exposure capacity without earning favorable risk-weighted treatment. Critics also note it can push risk-taking toward assets that carry higher risk weights but the same leverage-ratio cost, an unintended incentive regulators continue to monitor.

The total exposure measure behind the leverage ratio also captures a bank's derivatives book, typically using a standardized method for counting potential future exposure rather than just current market value. This matters because a bank can run a large notional derivatives portfolio with low current counterparty risk under ordinary conditions, yet still consume meaningful leverage-ratio capacity, since the measure is built to capture how exposure could grow if markets move sharply rather than only how things stand today.

• Basel Committee on Banking Supervision
• Bank for International Settlements