U.S. stock futures were mixed Monday morning, with Nasdaq 100 futures down more than 100 points. Applied Optoelectronics Inc. shares fell 11.9% to $109.99 in premarket trading after the company announced a $600 million at-the-market equity offering, a program allowing a company to sell shares gradually at prevailing market prices. RF Acquisition Corp II dropped 35.2% to $37.61 after surging 356% on Friday following SEC filings detailing the results of an extraordinary general meeting. Other notable premarket decliners included Zerostack Corp, ZKH Group, Jumia Technologies AG, Valneva SE, mF International Limited, Coherent Corp, SanDisk Corp, AXT Inc, Algoma Steel Group Inc, Lumentum Holdings PLC and Seagate Technology Holdings PLC.