Nov 1 (Reuters) - Australian shares inched up in choppy trading on Tuesday ahead of a key central bank interest rate decision, despite poor performance from Wall Street overnight, while software firm ReadyTech soared nearly 30% on a buyout offer.

The S&P/ASX 200 index rose 0.1% to 6,867.3. The benchmark ended up 1.2% on Monday.

Wall Street ended lower overnight, with major indexes falling as investors were reluctant to hold positions ahead of the Federal Reserve's policy meeting this week.

The Reserve Bank of Australia is expected to raise interest rates by a modest 25 basis points for the second straight month later in the day, according to a Reuters poll, despite the highest inflation in three decades.

Three of Australia's "Big Four" banks shed close to 1% each ahead of the decision, due at 0330 GMT. The broader financial index fell about 0.3%.

The mining index rose 0.63%, with lithium explorers leading the gains. Pilbara Minerals added 3%, while Allkem gained 2.3%.

Heavyweight miners such as Rio Tinto and BHP Group added 1% each despite weaker iron ore prices on Monday.

Shares of ReadyTech surged about 31.2%, after the company received a $308 mln buyout offer from a private equity firm.

Energy stocks added 0.4%, with sector major Woodside Energy gaining 0.8%. Origin Energy also rose 5.7%, extending gains to a second session, after posting higher quarterly revenue on Monday.

New Zealand's benchmark S&P/NZX 50 index fell about 0.1% to 11,329.53 in early trade.

The country's central bank said a preliminary analysis of its climate change stress test indicated river and surface water flooding may pose an even greater risk to lenders' residential mortgage portfolios than coastal flooding. (Reporting by Rishav Chatterjee in Bengaluru; Editing by Rashmi Aich)