Boeing Co.'s (BA) announcement Tuesday of another hold-up on its new 787 Dreamliner rattled investors already wary of problems surrounding the company's defense programs and pension cost headwind.

Shares of Boeing, which have sunk on worries about the 787 as well as the weak commercial aircraft market, traded recently at $43.57, down 7.1% for the day. That's well off the year's high of $76.48.

JSA Research cut Boeing's stock rating to hold from buy, saying it needs more clarity from Boeing on 787 plans.

"At this point, Boeing has provided us with nothing but uncertainty," said Paul Nisbet, president of the independent research company.

While the 787 is the focus of attention, Boeing has also suffered setbacks on the defense side of its business, which accounts for about half its $60 billion in annual revenue.

Boeing said the long-awaited first flight of the 787, to have taken place this month, would be delayed because the plane failed a stress test.

Boeing will need to reinforce a joint between the wings and body of the plane, Scott Carson, head of Boeing's commercial airplanes unit, said Tuesday. The fix is considered simple, and not related to manufacturing process or revolutionary materials used to make the 787, Carson said.

The company, which just last week confirmed the flight schedule, said it may take several weeks to redo its schedule for first 787 flight, and for first delivery of the aircraft, earlier planned for early 2010.

Nisbet said that, in the worst case, customers could have to wait months longer for the new planes, which are already two years behind their original schedule.

"We also have to consider how this will affect suppliers like Spirit, Rockwell Collins and Goodrich," he said. Typically, manufacturers like Boeing and rival Airbus must compensate both customers and suppliers when aircraft production is delayed. Shares of diversified suppliers Rockwell Collins Inc. (COL) and Goodrich Corp. (GR) were off less than 2% Tuesday, while Spirit Aerosystems (SPR), a Boeing spinoff, traded 6% lower at $14.11.

Boeing has already taken more than $1 billion of charges related to five delays on the 787, as well as for an updated 747 model.

Nisbet said JSA will re-evaluate its rating on Boeing when the plane maker provides more detail on the 787 program.

Boeing has more than 850 orders for the 787 from airline customers around the world, although the economic downturn has resulted in some cancellations this year.

While customers said Tuesday they were disappointed in the delay, they're not likely to walk away from Boeing. In recent years, both Boeing and Airbus have tripped over complexities related to the design and production of new aircraft. But cost savings on the 787, and Airbus A350, also long delayed, are worth waiting for, according to customers.

 
   Defense Business Also In Flux

Along with other U.S. defense contractors, Boeing has suffered program cutbacks as the U.S. government takes a hard look at defense spending.

Last year, Boeing lost a key contract to Airbus and its U.S. partner, Northrop Grumman Corp. (NOC), to build a new fleet of refueling tankers for the U.S. Air Force. Boeing successfully protested the contract award, and a new competition between the two rivals is expected to heat up later this summer. Funds for the $39 billion program have been approved.

Both Boeing and Airbus plan to modify commercial aircraft for military use. Speaking to reporters at the Paris Air Show last week, Pat Shanahan, head of Boeing's commercial aircraft programs, said "in Seattle, we consider the tanker program just as important as the 787."

Boeing also faces rising pension expenses. Analyst Brent Miller at Gradient Analytics said Boeing's pension fund this year is underfunded by $8.4 billion, which could hurt future earnings.

While a recovery in world's financial markets may help recoup some of that unrealized pension-fund loss, Boeing likely will be on the hook to increase pension contributions for the next several years, he said.

-By Ann Keeton, Dow Jones Newswires; 312-750-4120; ann.keeton@dowjones.com