The dollar recovered after its poorest weekly performance in three months, while the yen weakened after surging more than 3 percent.
U.S. crude prices on Monday settled sharply lower after briefly breaking below $40 a barrel for the first time since April.
Gold steadied on Monday, retreating from a near three-week high hit in the previous session.
U.S. stocks closed mixed Friday, the last trading day of the month, as encouraging earnings from major tech companies offset negative reports from some energy firms and a disappointing GDP report.
U.S. government debt yields were lower on Friday morning as U.S. gross domestic product for the second quarter missed economists' expectations.
European stocks recovered to close in the black on Friday as investors worked their way through another raft of European earnings.
Japan shares whipsawed and the yen surged after the BOJ threw markets a smaller-than-expected bone in its keenly watched decision on Friday.
Oil prices steadied on Friday amid short-covering after a week-long selloff but were on track to end the month about 15 percent lower.
Gold hit a near three-week high on Friday after much slower-than-expected U.S. economic growth weighed on the dollar.
The yen soared against the dollar after a round of modest monetary policy easing from the Bank of Japan disappointed investors.
U.S. stocks closed mostly higher Thursday, amid declines in oil prices, as major tech stocks gained.
U.S. government debt prices edged lower Thursday afternoon following the auction of $28 billion in seven-year notes.
European stocks finished in the red on Thursday as investors waded through another raft of earnings and prepared for the latest BOJ decision.
U.S. stock index futures pointed to a mostly lower open Friday amid earnings and after second-quarter GDP showed a 1.2 percent annualized growth rate.
Asia markets closed mixed on Thursday as investors digested fresh earnings reports and awaited the outcome of the Bank of Japan's two-day policy meeting.
Gold markets were mixed after the Fed stopped short of indicating that a further increase in interest rates is on the cards for this year.
The dollar fell against the yen as expectations faded of the Bank of Japan delivering a radical stimulus package this week.
Oil prices fall to a three-month low above $41 a barrel as producers continue to pump more than needed.
U.S. stocks closed mixed Wednesday after the Fed left rates unchanged. Gains in shares of Apple offset declines in Coca-Cola after their earnings reports.
U.S. 10-year sovereign yields continued to gain on Wednesday, with attention on better-than-expected U.K. economic growth data and the upcoming Fed announcement.