Investors are losing patience with Alcatel-Lucent SA Chief Executive Ben Verwaayen's efforts to turn around the struggling telecommunications-equipment maker.

Shareholder pressure on the Franco-American company's board to replace Mr. Verwaayen is running high, according to people familiar with the situation. The company surprised investors earlier this month by lowering its 2011 profit forecast when it reported third-quarter results. Its shares, already pounded since the summer, fell even more on the news and have now lost roughly two-thirds of their value since early July.

The company now has a market value of 3.2 billion ($4.3 billion).

Alcatel-Lucent officials recently have informally approached some potential outside successors to Mr. Verwaayen, people familiar with the matter said, though no official outreach has taken place.

Questions around the status of Mr. Verwaayen highlight the headwinds Alcatel-Lucent is up against. The company has struggled ever since it was formed by the merger of France's Alcatel and Lucent Technologies of the U.S. five years ago. It has been buffeted by obstacles to fully integrating the two businesses as well as fierce competition, spending cuts by customers