The sector's leverage to GDP growth remains a bullish driver. Growth prospects and perceived risks play a significant role in what is considered a “normal” or “fair” PE ratio. Companies expected to grow faster or perceived to be lower risk often command a higher multiple. In contrast, those facing headwinds or uncertainties may trade at a discount. Boeing Co. on Tuesday reported second-quarter revenue above forecasts as deliveries of commercial jets surged, but that wasn’t enough to encourage investors to bid up its stock after recent outperformance. Airline capacity utilization metrics back an optimistic jets stock price forecast, with load factors hitting multi-year highs across North America.