In Q4'25, Archer Aviation's (ACHR) operating expenses reached a peak of $234.4M USD, driven by R&D expenses of $147.1M USD and SG&A expenses of $87.3M USD, reflecting intensified investment in development and administrative activities. Over the period from Q1'23 to Q4'25, total operating expenses exhibited a strong upward trend, rising from $109.8M USD to $234.4M USD, with R&D costs showing consistent growth from $65.8M USD to $147.1M USD amid apparent scaling of innovation efforts. SG&A expenses displayed greater volatility, including an anomalous negative value of -$21.6M USD in Q3'23—potentially indicating a one-time adjustment—before stabilizing and surging to $87.3M USD by Q4'25, underscoring fluctuating overhead management in this stacked bar chart analysis.