Looking at the universe of stocks we cover at Dividend Channel, on 5/2/13, WestAmerica Bancorporation ( WABC) will trade ex-dividend, for its quarterly dividend of $0.37, payable on 5/17/13. As a percentage of WABC's recent stock price of $42.80, this dividend works out to approximately 0.86%, so look for shares of WestAmerica Bancorporation to trade 0.86% lower — all else being equal — when WABC shares open for trading on 5/2/13.Below is a dividend history chart for WABC, showing historical dividends prior to the most recent $0.37 declared by WestAmerica Bancorporation: In general, dividends are not always predictable; but looking at the history above can help in judging whether the most recent dividend from WABC is likely to continue, and whether the current estimated yield of 3.46% on annualized basis is a reasonable expectation of annual yield going forward. The chart below shows the one year performance of WABC shares, versus its 200 day moving average: Looking at the chart above, WABC's low point in its 52 week range is $40.50 per share, with $49.39 as the 52 week high point — that compares with a last trade of $42.80. According to the ETF Finder at ETF Channel, WABC makes up 1.37% of the High Yield Equity Dividend Achievers Portfolio ETF ( PEY) which is trading lower by about 1% on the day Tuesday. In Tuesday trading, WestAmerica Bancorporation shares are currently down about 0.4% on the day.