Under the terms of the deal, Network Data will acquire the share capital of MBSL for £2.2m while Manchester Building Society will take £250,000 worth of convertible preference shares in Network data.
An extraordinary general meeting will take place on December 9 to consider the details of the deal.
Network Data chief executive Richard Griffiths says: “We are delighted to have completed the largest merger of two mortgage networks since the inception of FSA regulation of the mortgage market four years ago in October 2004.
“Consolidation of the networks market is long overdue, and we expect the trend to accelerate with many of the smaller networks struggling in the current weak market conditions.”
He adds: “As the largest mortgage network we intend to play our part in this process and take advantage of the cost saving opportunities.
“We are pleased to welcome the Manchester Building Society as a significant shareholder in Network Data Holdings.”