Amazon.com Inc. is laying off more than 18,000 employees — the biggest reduction in its history — in the latest sign that a tech-industry slump is deepening.

Chief Executive Officer Andy Jassy announced the cuts, which represent about 1% of Amazon’s employees, in a memo to staff Wednesday, saying it followed the company’s annual planning process.

The eliminations began last year and were previously expected to affect about 10,000 people. The move is concentrated in the firm’s corporate ranks, mostly Amazon’s retail division and human resources functions, like recruiting.

Read more: Big Tech Layoffs Are Hurting Workers Far Beyond Silicon Valley

“Amazon has weathered uncertain and difficult economi…