Perth's BNK Banking Corp may have big - or bad - news for its shareholders this week; a capital raising probable.

Around lunch time Friday, local time, the ASX-listed self-styled neobank requested a trading halt in its securities.

There was a whiff of insider trading on Tuesday that saw the BNK share price spike 10 per cent to 66 cents, front-running a mostly bullish trading update the bank released on Wednesday.

This showed balance sheet lending up 50 per cent over one year to A$268 million and new business levels up twofold in the December quarter.

The BNK share price settled back to around 61 cents over the following days.

One enthusiast at the Hot Copper share trading gossip website rewrote the headline from Friday's trading halt notice as a "capital raising" this week, with the bank's most recent financials being one indicator that this is the likely news.

BNK's pillar 3 disclosure for the September 2019 quarter shows its total capital ratio fell around 140 basis points to 18.97 per cent over just three months, the bank's fast-growing mortgage book chewing through its capital base.

And pending far-off recovery from an insurance claim, BNK finds its pockets lightened from a recent $2 million fraud on a failed ATM business whose cash cartridges the bank stocked.

In November, the company disclosed that its related customers - ATM Co Pty Ltd and Tuff Enterprises Pty Ltd trading as Aus Guards “have informed BNK that ATM Co does not have the money in its account".

ATM Co and Tuff filed for insolvency in August.

The bank's lawyers remain on the hunt for the missing cash, while BNK last week said discussions with its "insurance providers continue to be constructive".