Skillful manipulators of Nasdaq's Small Order Execution System apparently struck again this week, adding fuel to a run-up in the stock of Zions Bancorp and Onbancorp.

Stocks of the two midsize banks spiked on Wednesday, a day when the industry's shares were flat. Zions, Salt Lake City, rose by nearly 5% to $48.25, a 52-week high. And Onbancorp, Syracuse, N.Y., rose by slightly more than 5%, to $28.375.

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