(Adds details, context surrounding offering)
By Christine Murray and Alexandra Alper
MEXICO CITY, Sept 12 (Reuters) - Mexico's Infraestructura Energetica Nova (IEnova) aims to raise more than $1 billion in a secondary share offering in October, three people with knowledge of the matter said, in what would be one of the biggest Mexican equity placements in recent years.
A unit of U.S. firm Sempra Energy, IEnova has hired Credit Suisse and JP Morgan to underwrite the offer that will help it fund major investments, according to two of the people, who declined to be named as the offering is not yet public.
A spokeswoman for IEnova declined to comment. Credit Suisse and JP Morgan also declined to comment.
IEnova is in the vanguard of Mexican companies that have pushed into the oil and gas industry since state oil firm Pemex lost its monopoly under a 2013 energy reform.
Since then, falling crude prices and budgetary constraints have forced Pemex to sell off assets. Last year, IEnova agreed to buy out the 50 percent stake owned by Pemex in pipeline company Gasoductos de Chihuahua for more than $1 billion.
That deal has now been restructured to satisfy regulators and should be completed in the third quarter, IEnova, which went public in 2013, said in a recent filing.
The company has won other big contracts such as a joint effort with TransCanada Corp to build and operate a natural gas pipeline from South Texas to Tuxpan in Mexico.
Chief Executive Carlos Ruiz said in July that IEnova planned to fund expansion through a mix of equity and long-term debt, but he gave no timing for the placement.
IEnova got shareholder approval in September last year to issue equity of up to 330 million additional shares. At the current share price of around 73 pesos, that would generate as much as 24.1 billion pesos ($1.27 billion).
However, secondary offerings are typically priced at a discount to the current trading price.
The planned offering would be the largest in Mexico since 2014, when real estate investment trust Fibra Uno issued 32.82 billion pesos ($1.74 billion) worth of investor certificates, according to data from the Mexican stock exchange.
Mexico's energy sector, particularly in infrastructure, has drawn some of the world's biggest investors, such as U.S. asset manager BlackRock, Canada's Caisse de depot et placement du Quebec and Goldman Sachs' private equity arm.
IEnova stock is one of the few ways investors can bet directly on the industry via Mexico's bourse.
IEnova has also been active in renewable energy, which the United States, Canada and Mexico in June agreed should account for 50 percent of power in the region by 2025.
This month it agreed to buy 100 percent of the Ventika wind farm in northeastern Mexico from investors led by private equity firm Blackstone for $852 million. ($1 = 18.9050 Mexican pesos) (Additional reporting by Roberto Aguilar; Editing by Dave Graham and Grant McCool)