NEW YORK (AP) — Shares of Timken Co. sank Thursday after the steel and ball bearings maker posted disappointing second-quarter results and lowered its estimates for the full year, saying its markets are not recovering as quickly as it expected.

Timken's net income decreased by more than half during the second quarter, and its revenue dropped 16 percent. It reported lower revenue from all of its divisions, saying off-highway, industrial distribution, and oil and gas demand all fell. Timken cut its forecast for the full year and said it expects a larger decline in sales. The company's had previously said it expected sales to bounce back in the second half of 2013.

Timken shares lost $3.76, or 6.3 percent, to $56.18 in afternoon trading. The stock has been trading around all-time highs in recent weeks as investors looked at the possibility that Timken will separate its two main business units.

The company said its net income skidded 55 percent in the second quarter, to $82.8 million, or 86 cents per share. A year ago Timken reported net income of $183.6 million, or $1.86 per share.

The Canton, Ohio, company said it earned 93 cents per share if one-time items are excluded, compared with $1.35 per share a year ago. Revenue fell to $1.13 billion from $1.34 billion. Analysts were expecting greater earnings of 97 cents per share and $1.18 billion in revenue, according to FactSet.

Timken said revenue from its steel business suffered the biggest decline, slumping 29 percent to $354.1 million. Revenue from its mobile industries unit fell 12 percent to $393.1 million and process industries revenue declined 6 percent to $317.4 million. Revenue from its aerospace segment revenue was down 6 percent to $82 million.

Timken's biggest shareholder, Relational Investors, in November revealed a proposal that Timken spin off the steel business into a separate company. Relational said the businesses don't fit together and a separation would be good for shareholders. Timken had resisted the suggestion, but in June the company said it formed a special committee on its board of directors that will consider the proposal.

For the full year Timken is now forecasting earnings of $3.30 to $3.60 per share. That estimate includes plant closure costs totaling 15 cents per share. It said revenue will fall about 10 percent, which suggests a total of $1.51 billion. The company had expected earnings of $3.75 to $4.05 per share including 20 cents per share in plant closure expenses, and said sales would fall around 5 percent to $1.59 billion.

Analysts had projected earnings of $3.96 per share and $4.66 billion in revenue on average.