CHICAGO (Reuters) – Boeing Co offered a weaker-than-expected 2011 earnings outlook as higher pension costs exacerbated the impact of potential defense spending cuts and delays to the 787 Dreamliner, sending its shares down 3.6 percent.

The company reported earnings on Wednesday that were largely in line with Wall Street's expectations, although revenue came in lower than analysts had expected.

"Obviously, the negative impact is the pension. That's the biggest issue," Wedbush Securities analyst Kenneth Herbert said, noting lower interest rates that have been a drag on some company pension programs.