BANKING

Big Banks Merging in Colorado: First Bank System Inc. said it is buying Colorado National Bankshares Inc., the state’s biggest independent commercial bank, in a stock swap worth $525 million. The deal will significantly expand Minneapolis-based First Bank’s presence in Colorado, raising its assets from $2.7 billion to $8 billion. Under the deal, Colorado National stockholders will receive 1.71 shares of First Bank System stock for each share they hold. The deal results in a price of $44 per share for Colorado National shareholders, the companies said, far above the closing price Friday.