Both Samsung and Sony, two of the world’s largest television makers, have begun enforcing minimum prices on their HDTV sets, in an effort to preserve profit margins, The Wall Street Journal reported. The plan could also protect retail chains such as Best Buy and Target from being undercut by online merchants such as Amazon. The new policy prevents U.S. retailers from advertising or selling televisions in stores or online for less than a certain price set by the manufacturers. The move comes after HDTV prices have fallen over the past three years, from an average of $644 in 2009 to $545 last year, representing a 15% decline. Samsung and Sony are taking a major risk and could lose sales to rivals LG, Panasonic and Sharp, which are still willing to let retailers offer deep discount on their sets.