Applied Materials Inc. suffered the worst single-day stock decline in five years after giving a disappointing sales and profit forecast, renewing concerns that the US trade dispute with China is weighing on demand.

Analysts wonder if China’s recent “overspending” on chip equipment is coming to a halt — and if the company is losing market share to rivals.

Applied Materials (AMAT) stock falls after the company issued guidance that fell short of Wall Street's expectations. Warren Buffett's Berkshire Hathaway (BRK-B, BRK-A) added to its stakes in homebuilder stocks Lennar (LEN) and DR Horton (DHI).

Beijing E-Town Semiconductor Technologies , a semiconductor equipment firm backed by Beijing's government, on Wednesday said it has sued U.S. chip equipment supplier Applied Materials over alleged trade secrets infringement.

Shares of Applied Materials Inc (NASDAQ: AMAT) tanked despite upbeat fiscal Q3 results. BofA downgraded, Goldman Sachs reiterated buy, Needham kept buy.

Applied Materials forecast fourth-quarter revenue and profit below estimates on Thursday, citing weak demand in China and erratic orders from customers facing uncertainty because of tariffs, sending its shares down nearly 13 per cent in extended trading.

Applied Materials was the worst-performing stock in the S&P 500 Friday, a day after the semiconductor equipment manufacturer gave weaker-than-expected guidance as global economic and tariff worries impact its business,

CNBC's Kristina Partisinevelos joins 'Squawk on the Street' to discuss the latest earnings from Applied Materials.