Today's biggest winners and losers in the stock market.

On this episode of Stock Movers:

- KB Home (KBH) shares are down 5% in postmarket trading Tuesday after the single-family home builder reported forecast deliveries for the second quarter that missed the average analyst estimate.

- Arm Holdings (ARM) which made its name licensing technology to semiconductor makers, will begin selling its own chips for the first time, adding a business that it expects to generate about $15 billion annually within five years. Shares closed down 1.41%.

- ImmunityBio (IBRX)shares plunged after the biotechnology company and its billionaire executive chairman, Patrick Soon-Shiong, were hit with a Food and Drug Administration warning letter for false and misleading promotion of its bladder cancer drug Anktiva.

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