Apart from government, Communist party and military officials, corporate executives from the energy sector have been the most frequent targets of the sweeping anti-corruption campaign.
The most senior leader to face formal corruption charges since the founding of the People's Republic in 1949 is former security tsar Zhou Yongkang, who rose through the ranks of state oil company China National Petroleum Corp and counted the energy sector as a key power base.
The probe into Mr Lu, who served on Bank of Beijing's board as a representative of Beijing Energy Investment Holding, may also be linked to Mr Zhou. Mr Lu was formerly chairman of Beijing Energy Investment, a major shareholder in Bank of Beijing. He had previously chaired a string of other energy companies. Mr Lu could not be reached for comment.
The turn towards the financial system also appears to be linked to probes into Mr Hu's former aide Ling Jihua and spymaster Ma Jian.
Founder Securities, China's ninth-largest brokerage by assets, said last month it had lost contact with chairman Lei Jie. A battle has raged in recent months between the brokerage's parent, technology and finance conglomerate Founder Group, and property developer Beijing Zenith Holdings.
Zenith said that Founder is linked to Mr Ling, while respected Chinese financial magazine Caixin quotes sources linking Zenith to Mr Ma.
In a series of postings on its official Weibo account, Zenith accused Founder Group executives of financial crimes including insider trading, market manipulation and illegally selling state assets.
Founder has denied the allegations. The disappearance of Mr Lei came days after the chairman and three top executives of Founder Group were ordered to co-operate with an official investigation and were replaced.