• The Reuters Tankan survey showed an increase in business optimism among large Japanese manufacturers, while confidence among non-manufacturers fell.
• Japanese authorities likely intervened in the currency market last Thursday and Friday, spending a total of 6 trillion yen ($37.9 billion) over the two days, according to Reuters.
• Singapore's non-oil domestic exports dropped more than expected in June, marking a fifth straight month of declines. They fell 8.7% year on year compared to a 1.2% decline expected by economists polled by Reuters.

Asia-Pacific markets traded mixed on Wednesday with Australia's S&P/ASX 200 reaching an all-time high, while an increase in business optimism among large Japanese manufacturers lifted Japanese stocks.

The Reuters Tankan manufacturing index came in at +11, up from +6 in the previous month. However, confidence among non-manufacturers dipped from +31 to +26.

Separately, Japanese authorities likely intervened in the currency market last Thursday and Friday, spending a total of 6 trillion yen ($37.9 billion) over the two days, according to Reuters.

The yen is currently at 158.36 against the U.S. dollar. The currency weakened to 161.82 last Wednesday before strengthening to as much as 157.41 the following day.

Japan's Nikkei 225 declined 0.43% to close at 41,097.69, while the Topix rose 0.37% to end at 2,915.21.

Australia's benchmark index closed the day 0.73% higher at 8,057.9. Gold miners Northern Star Resources and Bellevue Gold rose more than 3% and almost 2%, respectively. Evolution Mining and Newmont Corporation climbed more than 2%.

South Korea's Kospi dipped 0.8% to 2,843, while the small-cap Kosdaq lost 1.21%, closing at 829.41.

Hong Kong's Hang Seng index was up 0.15% in its last hour of trade, while China's CSI 300 rose marginally to end the session at 3,501.58.

The Taiwan Weighted Index fell 0.77% after a report cited U.S. Republican presidential candidate Donald Trump saying that Taiwan should pay the U.S. for defense.

"I know the people very well, respect them greatly. They did take about 100% of our chip business. I think, Taiwan should pay us for defense," Trump said in interview with Bloomberg Businessweek in June that was published on Tuesday.

Taiwan Premier Cho Jung-tai said that Taiwan was keen on being "more responsible" for its defense, and is steadily increasing spending, Reuters reported.

Shares of Taiwanese chip manufacturer TSMC fell as much as 2.36%.

HSBC Holdings announced on Wednesday that it has appointed Georges Elhedery as group CEO, with effect from Sept. 2. Elhedery, who is the company's chief financial officer, will replace Noel Quinn. The bank's Hong Kong shares were marginally down.

Singapore's non-oil domestic exports dropped more than expected in June, marking a fifth straight month of declines. They fell 8.7% year on year compared to a 1.2% decline expected by economists polled by Reuters.

On a month-on-month basis, Singapore's non-oil domestic unexpectedly dropped 0.4%, compared with a expectations of a 4.1% growth.

Overnight, Wall Street rose on optimism over possible rate cuts. The Dow blue-chip index gained 1.85%, closing at a record 40,954.48, while the broad-based S&P 500 added 0.64% to wrap the day at 5,667.20. The Nasdaq Composite rose 0.20%.

—CNBC's Pia Singh contributed to this report.

Clarification: This story was updated as Reuters revised its Tankan non-manufacturing survey numbers.