Activist investor Elliott Investment Management has built a stake exceeding $1 billion in Lululemon Athletica and is putting forward a potential CEO candidate, according to a person familiar with the matter. The news sent Lululemon’s shares up 6% in early trading Thursday. The move comes days after Lululemon announced that CEO Calvin McDonald will step down on January 31, following a year of declining performance. Elliott has reportedly been working with former Ralph Lauren CFO and COO Jane Nielsen as a potential successor. Nielsen previously held senior roles at Coach and PepsiCo. The activist stake signals growing pressure on Lululemon as it faces competition from brands like Vuori and Alo Yoga.