General Dynamics Corp., Reston, Va., purchased a group annuity contract to transfer $673 million in U.S. pension plan liabilities to two insurance companies. The aerospace and defense company disclosed the October purchase of the annuity contracts in its 10-K filing with the SEC on Feb. 7. General Dynamics did not disclose the names of the insurance companies, which now share the responsibility of paying benefits to about 16,000 retirees and beneficiaries. The transaction was completed using pension plan assets, according to the filing.