The slide in shares of companies that make components for data centers continued on Wednesday. A theme behind the multi-day underperformance in shares of companies like F5 Networks (FFIV), Finisar (FNSR), and Ciena (CIEN) may be the perception that internet companies like Amazon (AMZN), Microsoft (MSFT), and Google (GOOG, GOOGL) are starting to look to their own homegrown data center products.

The multi-day slide in these data center stocks seems to coincide with a downgrade of F5 on March 29 by Deutsche Bank. On that day, Deutsche Bank analyst Vijay Bhagavath downgraded F5 Networks to Sell and lowered his price target for the shares to $100 from $120. The analyst said he sees 30% downside from current levels based on fiscal year 2018 fundamentals. Bhagavath expects F5's Product and Services revenues to decelerate in FY18 based on secular headwinds. In his report, Bhagavath noted that the most imposing headwind for F5 are coming from the increasingly competitive load balancers from Amazon's AWS, Microsoft's Azure, and Google Cloud Platform.

Load balancers optimize application traffic across servers. Investors's Business Daily said in an article out that same day in late March: "Deutsche Bank downgraded F5 Networks to sell on Wednesday on views that Amazon and others are phasing out outside hardware suppliers as they use internal software to customize and control computer servers and, increasingly, other data-center infrastructure."

INTERNET GIANTS MAKE THEIR OWN PRODUCTS: "It's not unusual for internet and software giants to design and even make their own hardware, to increase efficiency and build a competitive advantage," said GeekWire in an article out January 19. According to GeekWire, Google designs its own servers and Facebook (FB) uses its homegrown switches in data centers. GeekWire added, "Amazon Web Services may have gone farthest down this path -- designing not only its own routers, chips, storage servers and compute servers but also its own high-speed network." Recent reports that Apple (AAPL), Amazon, and Google are competing for for Toshiba's (TOSBF) NAND flash memory unit add credence to the theme.

GOOGLE'S ESPRESSO: This past Tuesday, Google disclosed more details of Espresso, its software-defined networking strategy. Google Fellow Amin Vahdat said in a blog post, "Rather than relying on thousands of individual routers to manage and learn from packet streams, we push the functionality to a distributed system that extracts the aggregate information."

PRICE ACTION: Shares of data center infrastructure stocks continued their slide, with F5 Networks down 1%, Finisar down 5.5%, Oclaro (OCLR) falling 5.36%, Ciena losing 3.34%, NeoPhotonics (NPTN) down 1.4%, and Lumentum Holdings (LITE) fell 4.96%.