By 1625 London had already become a financial and trading center of international importance, and by the early eighteenth century it had outstripped Amsterdam as Europe's leading commercial city. London trade spanned the globe; the London stock market attracted international investors; while the Bank of England and the city's commercial insurance companies had also started to attract an international clientele. The most lucrative branches of overseas trade were controlled by monopolistic companies, of which the most important were the Merchant Adventurers (wool), the East India Company (spices, tea and other Asian items) and, after 1710, the South Sea Company (the slave trade to Spanish America). The most successful London merchants, who dominated these companies, accumulated fortunes comparable to those of great peers. A second tier, already numbering as many as a thousand individuals by about 1650, engaged in overseas trade but did not enjoy legal access to the monopolistic trades. Mercantile capital also supplied the Crown with vital loans. The great wars of William III and Queen Anne, between 1689 and 1712, helped fuel a further expansion of commercial investment and banking facilities, much of it centered around the London Exchange.