most money exists in the form of deposits and its supply is manipulated through the purchase of bonds. A third mechanism that central banks and governments can use to raise or lower the value of their currency is simply to talk it up or down, by hinting at future action that may discourage speculators. Quantitative easing, a practice used by major central banks in 2009, consisted of large-scale bond purchases by central banks. The desire was to stabilize banking systems and, if possible, encourage investment to reduce unemployment. As an example of direct intervention to manage currency valuation, in the 20th century Great Britain's central bank, the Bank of England, would sometimes use its reserves to buy large amounts of pound sterling to prevent it falling in value. Black Wednesday was a case where it had insufficient reserves of foreign currency to do this successfully. Conversely, in the early 21st century, several major emerging economies effectively sold large amounts of their currencies in order to prevent their value rising, and in the process built up large reserves of foreign currency, principally the US dollar. Sometimes the reserve account is classified as "below the line" and thus not reported as part of the capital account. Flows to or from the reserve account can substantially affect the overall capital account. Taking the example of China in the early 21st century, and excluding the activity of its central bank, China's capital account had a large surplus, as it had been the recipient of much foreign investment. If the reserve account is included, however, China's capital account has been in large deficit, as its central bank purchased large amounts of foreign assets (chiefly US government bonds) to a degree sufficient to offset not just the rest of the capital account, but its large current account surplus as well. Sterilization In the financial literature, sterilization is a term commonly used to refer to operations of a central bank that mitigate the potentially undesirable effects of inbound capital: currency appreciation and inflation. Depending on the source, sterilization can mean the relatively straightforward recycling of inbound capital to prevent currency appreciation and/or a range of measures to check the inflationary impact of inbound capital. The classic way to sterilize the inflationary effect of the extra money flowing into the domestic base from the capital account is for the central bank to use open market operations where it