Aug 11 (Reuters) - Australian shares touched an all-time high on Wednesday, boosted by a solid earnings update from the country's largest lender and strong gains in banking and mining stocks.

The S&P/ASX 200 index rose 0.4% to 7,593 at 0042 GMT, after having closed at a record high on Tuesday. In other markets, Japan's Nikkei rose 0.61% to 28059.56, while S&P 500 E-minis futures were down 0.03%.

Australia's largest lender Commonwealth Bank of Australia (CBA) doubled its dividend to A$2 and announced a share buyback of A$6 billion ($4.41 billion) while reporting a 20% jump in full-year profit to A$8.65 billion.

Shares of CBA gained as much as 2.3% to hit a record high, while Australia and New Zealand Banking Group added 1.1%. The gains helped the financial sub-index rise 0.8%.

Iress Ltd was the top gainer on the benchmark index, climbing as much as 5.6%, after it received a revised buyout offer from Sweden-based private-equity firm EQT to buy the software provider for an enterprise value of A$3.2 billion.

Insurance Australia Group rose 1.7% after committing to pay a dividend of 13 Australian cents per share, despite posting a loss of A$427 million for the previous financial year.

Local miners rose 1.23%, even as iron ore prices slumped on concerns about weakening Chinese demand.

Iron ore miners Mount Gibson Iron Ltd and coal miner Coronado Global Resources Inc led the gains on the sub-index, gaining 4.55% and 4.15%, respectively.

Across the Tasman Sea, New Zealand's benchmark S&P/NZX 50 index rose 0.07% to 12,772.9. ($1 = 1.3611 Australian dollars) (Reporting by Riya Sharma in Bengaluru; editing by Uttaresh.V)