General Electric said Monday that its longtime chief executive, Jeffrey R. Immelt, would retire at the end of this year, closing out a 16-year run at the helm of the industrial giant.

Immelt’s tenure included a vast overhaul of the conglomerate’s portfolio but also an underperforming stock price that has trailed well below market indexes and competitors.

General Electric is the only remaining member of the original Dow Jones industrial average, created in 1896 by Charles Dow. In the past, its very makeup – electric light bulbs, appliances, NBC – gave GE a touch point to hundreds of millions of Americans and consumers worldwide.

Because of its size and ability to generate cash, the U.S. economy and the millions of pensioners, savers and investors have depended on the success of the General Electric stock price and dividend – whether they knew it or not.

Immelt’s inability to move that stock price – it fell by nearly half during his tenure – was thought by many to be his undoing.

“Why the change? Two words: stock price,” said Ivan Feinseth, chief investment officer at Tigress Financial Partners.

“There is no question. The board and shareholders have given Jeff Immelt a long time. He was CEO for almost 17 years in one of the biggest upmarkets cycles in history and the stock has underperformed,” Feinseth said.

Immelt, 61, will be succeeded on Aug. 1 by John Flannery, the current president and chief executive of the company’s health-care business, and will remain chairman until the end of the year. The company said that the announcements were part of a succession plan that had been in place since 2011, and that now was an “ideal time for change.”

The announcement comes amid recent pressure from activist investor Nelson Peltz’s Trian Fund Management, which had pushed GE to cut costs and change up the executive compensation bonus plan.