According to the Wall Street Journal, which cited unnamed sources familiar with the matter, the focus of the probe is aimed at the accounting practice.
SEC officials are also investigating whether a failure by the bank to mark down the value of a real estate portfolio, which it acquired during the takeover of Archstone-Smith Trust, may have impacted the bankâs financial stability.
The news provider claimed that the renewed focus of the probe could mean that civil charges could be filed soon by the regulator.
A number of officials including former chief executive officer Dick Fuld have been questioned by investigators during recent weeks.
The Repo 105 process is a way for banks to keep debt off their balance sheets and was criticised earlier in the year by a report into the bankruptcy of Lehman Brothers by Anton Valukas.
Mr Valukas described Repo 105 as âaccounting gimmickâ in his analysis of the reasons behind Lehman Brothersâ failure.
Ernst & Young, the auditing firm for Lehman Brothers, is also under investigation by the SEC.
By Jim Ottewill