Silicon Laboratories Inc. (SLAB - Free Report): This is a leading provider of silicon, software and solutions for the Internet of Things, Internet infrastructure, industrial automation, consumer and automotive markets. It also delivered incredible returns of 31.9% in the month. The stock has a Zacks Rank #3 and a VGM Score of D. SLAB accounts for 0.7% of SOXX.

Marvell Technology Group Ltd. (MRVL - Free Report): This is a leading designer, developer and supplier of mixed-signal and digital signal processing integrated circuit for high-speed, high-density, digital data storage and broadband digital data networking markets. The stock rose about 26.8% in the month. It currently carries a Zacks Rank #4 (Sell) and has a VGM Score of D. MRVL makes up for 2.6% of the total assets.

Teradyne, Inc. (TER - Free Report): This company is a leading supplier of automation equipment for test and industrial applications. The stock makes up for 4.7% of the assets in the SOXX portfolio. It gained 23.2% in April. Teradyne sports a Zacks Rank #1 (Strong Buy) and VGM Score of D.

Microchip Technology Incorporated (MCHP - Free Report): This company develops, manufactures and sells specialized semiconductor products used by customers for a wide variety of embedded control applications. The stock rallied 19% in the month and accounts for 3.7% allocation. Microchip Technology has a Zacks Rank #3 and VGM Score of B.