Led by Lockheed Martin Corp. (LMT), the biggest U.S. defense companies are trading at record prices as shareholders reap rewards from escalating military conflicts around the world. Investors see rising sales for makers of missiles, drones and other weapons as the U.S. hits Islamic State fighters in Syria and Iraq, said Jack Ablin, chief investment officer at Chicago-based BMO Private Bank. As we ramp up our military muscle in the Mideast, there's a sense that demand for military equipment and weaponry will likely rise," said Ablin, who oversees $66 billion including Northrop Grumman Corp. (NOC) and Boeing Co. (BA) shares. "To the extent we can shift away from relying on troops and rely more heavily on equipment -- that could present an opportunity." Bombardments of Islamic State strongholds added to tensions this year that include U.S.-led sanctions on Russia for backing Ukrainian rebels. The U.S. also is the biggest foreign military supplier to Israel, which waged a 50-day offensive against the Hamas Islamic movement in the Gaza Strip. A Bloomberg Intelligence gauge of the four largest Pentagon contractors ... rose 19 percent this year through yesterday, outstripping the 2.2 percent gain for the Standard & Poor's 500 Industrials Index. Lockheed, the world's biggest defense company, reached an all-time high of $180.74 on Sept. 19, when Northrop, Raytheon Co. (RTN) and General Dynamics Corp. (GD) also set records. That quartet and Chicago-based Boeing accounted for about $105 billion in federal contract orders last year. U.S. lawmakers including Representative Peter King, a New York Republican, have suggested that the new global threats could prompt Congress to reconsider planned reductions in defense spending.