Check out the companies making the biggest moves midday: Miami International Holdings — The parent of Miami-based exchange operator MIAX surged more than 43% in its public market debut at the New York Stock Exchange. The company priced its initial public offering at $23 per share. It last traded above $31. Paramount Skydance — The media company fell more than 6%, giving back some of Wednesday's stunning surge. Paramount rallied 37% in the previous session, marking its best day ever. Amcor — The packaging company plummeted more than 14% after its fiscal fourth-quarter results missed analysts' estimates. The company earned 20 cents per share on revenue of $5.08 billion. That's below the StreetAccount consensus of 22 cents per share in earnings and $5.19 billion in revenue. Its full-year guid

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