The shares of Boeing (BA: sentiment, chart, options) hit a new 52-week low of $69.83 following some bearish commentary from Goldman Sachs. The brokerage firm slashed its rating on BA from "neutral" to "sell," and lowered its price target from $88 to $60. To emphasize the severity of the move, Goldman also added Boeing to its "conviction sell" list.

The ratings adjustment was part of a broader downgrade on the entire aerospace sector, which Goldman lowered from "neutral" to "cautious." The analysts see as much as 20% downside from the sector's current levels. Aerospace orders are expected to fall by 50% in 2008 and 2009.

In a note, the brokerage firm didn't mince any words in making unfavorable comparisons: "We think the market is not factoring in that the combined effect of accelerated crude prices, a weak economy, and rapidly deteriorating airline fundamentals could pose a worse problem for the Aerospace group than 9/11 and SARS."

At midday, BA's loss of nearly 6.5% is serving as an anchor around the Dow's neck. The broader Dow Jones Industrial Average (DJIA) is clinging to a modest gain of 46 points at last check.