Sell alert! Why this expert is calling time on Westpac and CBA shares

Westpac Banking Corp (ASX: WBC) and Commonwealth Bank of Australia (ASX: CBA) shares have both underperformed the 2.3% 12-month gain posted by the S&P/ASX 200 Index (ASX: XJO) earlier this week.

In fact, both of the big four ASX 200 bank stocks are well into the red since this…