By Christina Farr SAN FRANCISCO (Reuters) – Apple Incs iPad is losing steam just four years after its release, but an alliance with International Business Machines Corp could rejuvenate a flagging product by entering into a largely untapped corporate market. Apple shipped 13.2 million iPads in the June quarter, 8 percent fewer than a year earlier and lagging Wall Streets forecast for 14 million or more. Apple helped create the tablet market in 2010 with its first iPad. Chief Executive Officer Tim Cook described iPad sales as very bifurcated – they continue to grow at 50 percent or above in emerging markets such as the Middle East and China, but in developed countries like the United States, the market is weaker. Research firm IDC lowered its forecast for 2014 worldwide tablet demand growth to 12.1 percent – a fraction of the 51.8 percent expansion of 2013.