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TORONTO, March 19 (Reuters) - Bank of Montreal (BMO.TO: Quote, Profile, Research) said on Wednesday that it has reached agreements with four swap counterparties and certain investors to restructure its Apex and Sitka commercial paper trusts, which did not meet their payment obligations last month and failed to satisfy collateral calls.

BMO said that it does not expect to take further writedowns on its remaining C$495 million ($490 million) investment in the trusts.

The bank, Canada's fifth largest by market value, said that under the planned restructuring, the term of the Apex and Sitka notes would be extended to maturities ranging from about five to eight years.

BMO sponsored the two asset-backed commercial paper trusts, which provide credit default swap protection on leveraged super senior tranches of a pool of U.S. and European corporate credits, according to the bank's latest quarterly report.

"The restructuring will avoid unnecessary losses and will preserve the trusts' underlying positions, the quality of which are AAA," Tom Milroy, chief executive of BMO Capital Markets, said in a statement.

After the restructuring, BMO's total investment in the subordinated notes of the trusts will be about C$815 million.

It will also provide about C$850 million of an additional C$1.15 billion senior funding facility to satisfy collateral calls, and has advanced C$200 million of this amount.

After evaluating the credit quality of roughly 450 obligations in the trusts, the bank said it considers the risk of credit loss to BMO to be low.