* Energy stocks top losers as oil prices tumble overnight

* "Big four" banks drop between 1.7% to 2%

* NZ business sentiment improved in Sept - ANZ Bank survey

Sept 30 (Reuters) - Australian shares fell on Wednesday, tracking overnight Wall Street losses, as investors pulled out of risky bets ahead of the first U.S. presidential debate, even as the domestic COVID-19 situation improved.

The S&P/ASX 200 index dropped up to 1.5% in early trade and was on track for a third straight day of losses, after Wall Street closed lower on Tuesday, snapping a three-day winning streak.

Global developments largely overshadowed an improving coronavirus situation in Australia's hotspot of Victoria state, where 13 new cases were reported on Wednesday, far less than a peak of more than 700 cases logged in early August.

Barring a 0.7% gain by gold stocks, all major sub-indexes were trading in the red.

Energy stocks, down as much as 2.1%, were the top losers among sectors due to an overnight 3% drop in oil prices over demand concerns.

Whitehaven Coal lost up to 6.4% and was the top percentage loser on the sub-index, followed by Viva Energy , down 4.5%.

Sector heavyweight Santos fell 3%, despite a state panel approving its A$3.6 billion ($2.57 billion) Narrabri gas project.

Tech stocks halted a three-day winning streak and fell up to 1.6%, with losses in EML Payments and Afterpay weighing on the sub-index.

Financials extended their losing streak to a third session. The "big four" banks slipped between 1.7% and 2%.

In New Zealand, the benchmark S&P/NZX 50 index fell 0.4% to 11,699.14 by 0105 GMT.

Shares of a2 Milk hit their lowest in over six months, and were the top drag on the benchmark for the third consecutive day after projecting a bleak earnings outlook on Monday.

The country's business sentiment improved in September amid growing confidence that the COVID-19 outbreak is under control, an ANZ Bank survey showed.

(Reporting by Arundhati Dutta in Bengaluru; Editing by Rashmi Aich)