The CEOs of semiconductor maker Nvidia and chip equipment manufacturer Lam Research sold millions of dollars worth of their own stock at end of June and the start of July, according to securities filings and information compiled by VerityData as of Wednesday. Nvidia CEO Jensen Huang sold $59.65 million worth of stock on June 28 and July 1. Lam Research CEO Timothy Archer sold $31.04 million worth of shares on June 28. Both executives made their sales under 10b5-1 trading plans. The plans establish a predetermined price and time for executives to sell their shares in the future. June 28 marked the final trading day of the first half. Nvidia shares gained more than 150% during the first six months of the year, reaching $1,220 in early June before the company split the stock 10-for-1 . Insider buying and selling is closely tracked by professional fund managers. The idea is that these trades could possibly be a signal about what an executive or board member thinks of the direction of the company, the valuation of the stock or how its industry is faring. Here are the other biggest recent insider sales, according to VerityData and securities filings: Nvidia CEO Jensen Huang sold 480,000 shares at an average price of $124.27 for a total of $59.65 million. Trades were made pursuant to a 10b5-1 trading plan adopted in March and are part of ongoing sales. Lam Research CEO Timothy Archer sold 29,000 shares at an average price of $1,070 for a total of $31.04 million. Trades were made pursuant to February 10b5-1 trading plan. Adobe Systems CEO Shantanu Narayen sold 25,000 shares at $544.11 each for a total of $13.6 million. Juniper Networks CFO Kenneth Miller sold 80,000 shares at an average price of $36 for a total of $2.88 million. Trades were made pursuant to a 10b5-1 trading plan adopted in February. The trades reduced total holdings by 32%, according to Verity. Consol Energy CEO James Brock sold 17,400 shares at $100.85 apiece for a total of $1.75 million. Trades were made under 10b5-1 trading plan enacted last September. Tegna CEO David Lougee sold 98,400 shares at $13.98 a piece for a total of $1.38 million. Trades were made pursuant to a 10b5-1 trading plan dating from last August. Lougee will reportedly step down as CEO this summer, remaining a senior advisor. —CNBC’s Nick Wells contributed to this report.