The demand of Qualcomm Snapdragon S4 processor is very high. It makes Qualcomm have to partnered with Samsung to produce additional supply.
Qualcomm is a fabless chip designer and currently it contracts Taiwan Semiconductor Manufacturing (TSMC) to build the new design of its 28nm process chipset. However, because it can not meet the orders, Qualcomm and Samsung have signed an agreement and now we will see Samsung also produces chips for Qualcomm.
Consideration of this decision is because Samsung is the manufacturer of Exynos chip and the Qualcomm Snapdragon S4 itself used by Samsung in Galaxy S III 4G LTE for US market. The success of Galaxy S III sales in US makes Qualcomm choose Samsung although they are rival. Qualcomm believes by partnering with Samsung, the production of Snapdragon S4 will increase and meet the market demand.