NEW YORK (AP) -- Shares of Motorola Mobility Holdings Inc. were heading lower in early trading Friday after it provided a third-quarter outlook substantially below the figures analyst were looking for.The maker of cell phones and cable set-top boxes, which split off from the rest of Motorola in January, posted second-quarter results above expectations, but still appears to be struggling in its turnaround.The shares were down $1.80, or 7.9 percent, at $21.11 in morning trading.Motorola's smartphone shipments grew only 7 percent from the first quarter, compared to about 50 percent for Samsung Electronics and probably more than 20 percent for HTC Corp., according to Sanford Bernstein analyst Pierre Ferragu.Both Samsung and HTC companies base their smartphones on the same software Motorola uses, Google Inc.'s Android.Motorola appears to be losing market share in the U.S. market, Ferragu said, which he sees as potentially worrisome. The U.S. market is a trendsetter in the wireless world.Ferragu also noted that Motorola has a negative 1.3 percent operating margin on the phones, weaker than expected."We recommend investors staying away from the name," he wrote in a morning research report.Motorola posted a loss of $56 million, or 19 cents per share, for the second quarter. That compares with a profit of $80 million a year earlier.For the third quarter, Motorola expects adjusted earnings to range from break-even to 10 cents per share. Analysts were looking for 27 cents per share.