Carl Icahn has recently acquired a leading equity position in Newell Brands, three sources close to the situation told The Post. The previously undisclosed position taken by the hard-charging billionaire, could put him in position to have a key role in deciding the winner of an ongoing proxy fight involving the Hoboken, NJ, maker of Rubbermaid storage containers, Graco baby strollers and Rawlings baseball gloves. Activist hedge fund Starboard Value announced on Feb. 12 it was nominating 10 directors and demanded a new chairman and CEO for the company, whose shares have skidded 47 percent in the last year.