Cullen/Frost ( CFR) agreed to acquire Summit Bancshares ( SBIT) for about $363.5 million.

Summit is the holding company parent of Summit Bank, a $1.1 billion-in-assets commercial and consumer lender based in Fort Worth, Texas. Cullen/Frost, with $11.6 billion in assets, is based in San Antonio.

Summit shareholders will receive either cash or Cullen/Frost stock worth $11.50 plus 0.2933 of a Cullen/Frost share, for a total value of about $28.31 per Summit share. Summit's stock closed Friday at $21.21 each and was halted for trading Monday morning.

The transaction should start adding to Cullen/Frost's GAAP earnings per share beginning in 2007 and is expected to close in the fourth quarter of 2006.