Bets against Australia's Big Four banks have piled up amid rising concerns that the country's property prices could be about to fall off a cliff.
The value of shares in the Big Four - Australia & New Zealand Bank (ANZ), Commonwealth Bank of Australia (CBA), National Australia Bank (NAB) and Westpac - that were sold short totted up to 9.03 billion Australian dollars ($6.52 billion) as of May 16, up 85 percent since the start of the year, according to data from the Australian Securities and Investments Commission (ASIC).
About 3 percent of Westpac's and ANZ's shares have been sold short, while about 2 percent of CBA and NAB shares were short sold, the data showed.
So far this year, NAB's shares are down nearly 7 percent and CBA's are off almost 9 percent, while Westpac and ANZ are down more than 10 percent each by Monday's close. That's a sharp underperformance against the broader S&P/ASX 200 index, which was up 0.4 percent for the year by Monday's close, even though the banks are heavily weighted in the benchmark.
Concerns over the banks has being driven in part by Australia's long-bubbly property market.