Exxon Mobil Corp. (NYSE: XOM), the biggest U.S. energy company, plans to invest $185 billion to develop new energy sources aimed at meeting increased global demand, Chairman and Chief Executive Rex Tillerson told investors Thursday.

Through 2016, Exxon Mobil plans to invest nearly $37 billion annually in its energy portfolio, Tillerson said in a presentation at the New York Stock Exchange.

The company's shares fell $1.01 by midafternoon to $84.82, about 3.8 percent below their 52-week high. The price of a barrel of crude oil on the New York Mercantile Exchange rose 84 cents to $107.

The stock's decline could be due, at least in part, to Tillerson's showing a slide that indicated the Irving, Texas, giant warned of a possible 3 percent drop in output this year, Bloomberg News reported.

 An unprecedented level of investment will be needed to develop new energy technologies to expand supply of traditional fuels and advance new energy sources, said Tillerson, 59, who joined Exxon Mobil after graduating with a civil-engineering degree from the University of Texas in 1975.  We are developing a diverse portfolio of high-quality opportunities across all resource types and geographies.

Exxon Mobil expects that by 2040 global energy demand will have increased 30 percent above the level in 2010. The world's increased thirst for energy will make natural gas the fastest-growing source. Together with oil, it's expected to meet 60 percent of energy needs in the coming decades, Tillerson said.

During Thursday's presentation, the CEO said his company intends to launch 21 major oil and natural gas endeavors within two years. By the end of 2013, he said, Exxon Mobil wants to launch an additional nine projects -- in West Africa, Kazakhstan and Canada.

The company also intends to produce an additional 1 million barrels of oil a day by 2016.

During challenging times for the global economy, Exxon Mobil continues to invest to deliver the energy needed to underpin economic recovery and growth, Tillerson added.

Last year, Exxon Mobil reported that profits rose 34 percent to $41 billion from $30.4 billion in 2010.  It also spent a record $36.8 billion on exploration, an increase of 14 percent over 2010. 

The oil giant was able to replace 107 percent of its 2011 production because it added 1.8 billion barrels of oil to proven reserves. 

Exxon Mobil, the world's second-most-valuable company, has a market capitalization of $400.6 billion.