(CNBC) — Bank shares fell broadly on Wednesday amid growing concerns that the recent Republican electoral losses could hinder the party’s push to reform the U.S. tax code. They have also been pressured by a flattening yield curve.

The SPDR S&P bank exchange-traded fund (KBE) fell 0.7 percent and notched its fourth straight negative session. Bank of America was among the worst performers in the ETF, sliding 1.5 percent.

The banks fell after Republicans lost key elections in New Jersey and Virginia on Tuesday. These losses increase uncertainty around the GOP’s plans to move forward with tax reform.

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