The Bank of Japan adopted quantitative easing on 19 March 2001. Under quantitative easing, the BOJ flooded commercial banks with excess liquidity to promote private lending, leaving them with large stocks of excess reserves and therefore little risk of a liquidity shortage. The BOJ accomplished this by buying more government bonds than would be required to set the interest rate to zero. It later also bought asset-backed securities and equities and extended the terms of its commercial paper-purchasing operation. The BOJ increased commercial bank current account balances from ¥5 trillion to ¥35 trillion (approximately US$300 billion) over a four-year period starting in March 2001. The BOJ also tripled the quantity of long-term Japan government bonds it could purchase on a monthly basis. However, the seven-fold increase notwithstanding, current account balances (essentially central bank reserves) being just one (usually relatively small) component of the liability side of a central bank's balance sheet (the main one being banknotes), the resulting peak increase in the BOJ's balance sheet was modest, compared to later actions by other central banks. The Bank of Japan phased out the QE policy in March 2002.