Lockheed Martin Corp. LMT faces growing pressure from Wall Street after delivering mixed second-quarter results and absorbing nearly $1.6 billion in charges across key segments.Goldman Sachs analyst Noah Poponak reiterated a Sell rating on Lockheed Martin and lowered his 12-month price forecast to $398 from $406. He pointed to ongoing problems that could hurt profits, reduce cash flow, and make future earnings less predictable.Poponak noted that the latest charges in classified Aeronautics and helicopter pr ...