 Shares of Lumentum Holdings Inc. LITE, -1.65 were falling 15 in premarket trading Tuesday after the optoelectronics company, which is a supplier to Apple Inc. AAPL, 0.39 , delivered a downbeat forecast amid supply challenges. The company posted a fiscal first-quarter net loss of about 400,000, or 1 cent a share, whereas it recorded net income of 81.5 million, or 1.08 a share, in the year-earlier period. 