"But surprisingly, they've consistently cut US$10 billion each of the last four times they've met, and that's a sign to some that we might even have an earlier rate hike than thought."
In the final hour of trading in New York, the Dow Jones Industrial Average rose 0.21 per cent, the Standard & Poor's 500 Index gained 0.29 per cent, while the Nasdaq Composite Index advanced 0.52 per cent.
"Overall, you're still in a market environment where the path of least resistance is up," John Canally, an economic strategist at LPL Financial, told Bloomberg News. "Another bump tomorrow could be the [Federal Open Market Committee], although the outcome is largely already priced in."
Gains in shares of Home Depot, up 1.7 per cent, Goldman Sachs, up 1.6 per cent, and JPMorgan Chase, up 1.2 per cent, propelled the Dow higher.
Oil rose as fighting in Iraq continued to escalate. Brent for August settlement added 0.5 per cent to US$113.49 a barrel on the ICE Futures Europe exchange.
"The Iraq situation could continue to destabilise markets, and there are a lot of unknown factors that could keep oil prices elevated," Bernard Baumohl, a managing director at the Economic Outlook Group in Princeton, New Jersey, told Reuters. "That said, valuations for stocks are not alarmingly high, and there aren't many alternatives for investors."
In Europe, the Stoxx 600 Index finished the session with a 0.3 per cent gain from the previous close. The UK's FTSE 100 increased 0.2 per cent, Germany's DAX strengthened 0.4 per cent, while France's CAC 40 added 0.6 per cent.
A report showed that German investor confidence unexpectedly slid for a sixth straight month. The ZEW Center for European Economic Research's index of investor and analyst expectations fell to 29.8 this month, down from 33.1 in May.