What it is
OpEx covers the bills the company pays to keep the lights on and the business growing. Three big buckets:
- SG&A — Selling, General & Administrative. Office rent, executive pay, legal, finance.
- R&D — Research & Development. Engineers building the next thing.
- Sales & Marketing — campaigns, sales-team commissions, advertising.
Why people watch it
OpEx tells you how much overhead the business carries. A growing OpEx isn't automatically bad — companies invest in R&D and marketing because they expect future revenue from it. The question is whether revenue is growing at least as fast.