* Banks account for most losses
* Construction firms drop after Adelaide Brighton's profit warning
* Lynas leads gains on heightened trade war concerns
By Aditya Soni
July 31 (Reuters) - Australian shares slipped on Wednesday, with banks and construction stocks dominating the losses, as investors booked profits after the benchmark closed at an all-time high in the previous session.
The S&P/ASX 200 index .AXJO ticked 0.3% or 21.9 points lower to 6,823.2 by 0208 GMT. The benchmark firmed 0.3% to a record close on Tuesday.
"The markets have been trading at a record high, so there's a bit of profit taking going on," Damian Rooney, director of equity sales at Argonaut, said.
Losses were dominated by financial stocks, with top lender Commonwealth Bank of Australia CBA.AX dropping 0.7%, its sharpest intraday fall in more than two weeks.
Other members of the "Big Four" slid between 0.3% to 0.8%.
Meanwhile, Australian shares of British lender CYBG PLC CYB.AX fell 10.9% to nearly six-month lows following a reported dip in mortgage loans and shrinking net interest margins. manufacturer Adelaide Brighton Ltd ABC.AX lost a fifth of its value and was the worst performer on the benchmark after it flagged weaker annual earnings and scrapped its interim dividend. (Adelaide Brighton) is a significant bellwether in this space, and the comments they made about the softening market are a serious concern for all the industrial and residential and civil construction sectors," Rooney said.
The gloomy warning spooked investors, leading to a heavy sell-off in construction stocks, with CSR Ltd CSR.AX falling to a more than four-week trough, while Boral Ltd BLD.AX posted its biggest intraday loss since Feb. 4.
Meanwhile, a trade threat from President Donald Trump to China cast a pall on the broader risk-sentiment. The warning came as officials from both sides meet in Shanghai for the first round of talks after the world's biggest economies agreed to a truce at the G20 summit last month.
The heightened trade war concerns bolstered interest in rare earths miner Lynas Corporation Ltd LYC.AX , which saw its best day in nearly four weeks.
Commercial explosives supplier Orica Ltd ORI.AX jumped to a more than four-year high and was among the top gainers on the benchmark.
Brokerage Morgans raised Orica's price target following upbeat commentary from the company's management after its investor day presentation. New Zealand, the benchmark S&P/NZX 50 index .NZ50 rose 0.4% to a record high of 10,916.50.
Dairy firm a2 Milk Company Ltd ATM.NZ climbed 1%, on track for its third consecutive session of gains and was among the top boosts to the benchmark.
(Additional Reporting by Syed Saif Hussain Naqvi; Editing by Jacqueline Wong)