ARM HOLDINGS PLC

ARM Holdings has 61 institutional holders in this quarter's 13F data, and the top two alone account for 77% of the $431.8 million in tracked value — moving in opposite directions. Hyperion Asset Management, the largest holder, cut its position by two-thirds, from 1,598,537 to 531,331 shares (-$53.4 million), while Congress Asset Management appeared with a brand-new $145.0 million stake (409,049 shares), immediately becoming the second-largest holder. Congress's new position alone is more than 45 times the size of the next-largest new entrant. Two smaller holders also cut sharply: Defender Capital reduced its stake 79.2% (-$7.7 million) and Covea Finance cut 79.0% (-$2.3 million). On the buying side, Ardsley Advisory Partners more than doubled its position (+161%, from 18,000 to 47,000 shares, +$13.9 million), and UNICOM Systems held its 89,000 shares flat while the position's value rose $18.1 million on price alone. With one major holder selling two-thirds of its stake and another building a nine-figure position from nothing in the same quarter, ARM's institutional ownership base is being substantially reshuffled rather than simply growing or shrinking.