Southeast Asian stock markets edged up on Wednesday, with Thailand leading the gains, as hopes of a widely anticipated rate cut by the US Federal Reserve later in the day boosted risk sentiment.

The US central bank's likely 25 basis point trim would mark Fed's third rate-cut this year, while investors would keenly watch Chairman Jerome Powell's post-meeting conference to take cues for future policy easing stance.

There is a "growing sense, and hints from the Fed, that there may be scope, perhaps even solid justification, for one more 'insurance' cut at this juncture," Mizuho said in a note.

Chinese foreign ministry's statement that top Chinese and US trade negotiators will speak soon in relation to signing an interim trade deal also aided the positive sentiment.

This comes after Reuters reported on Wednesday that a stopgap agreement between the United States and China might not be completed in time for signing in Chile next month as expected.

The Thai benchmark advanced 0.7% to lead the pack in the region, underpinned by gains in financial and energy stocks. Bangkok Bank PCL scaled 6% while oil and gas major PTT Exploration and Production PCL rose 3.4% after posting a jump in quarterly net profit.

The Vietnamese index ended 0.5% higher, buoyed by financial stocks. Lenders Vingroup JSC and Vietcombank rose over 1.5% each.

The Philippine index reversed course to end 0.4% higher, on last-minute buying in index heavyweight stocks.

BDO Unibank Inc and Metropolitan Bank and Trust Co were among the top gainers as they added 2.4% and 2.2%, respectively.

Singapore's main index also edged up 0.3%, with financials dominating gains on the benchmark. Southeast Asia's biggest lender DBS Group Holdings Ltd rose 1.3%, while Oversea-Chinese Banking Corp Ltd added 1%.

Meanwhile, Indonesian shares were little changed ahead of its October inflation data, which is expected to slow down from a month earlier, a Reuters poll showed.