Bull markets end due to recession, Fed hiking rates, or intense FOMO-driven capital markets activity. Recession risk is fading, Fed hikes are off the table (oil decline helps), long-end yields moving higher is not happening, and FOMO is still ahead. Earnings power is much greater than expected, so multiples are not stretched despite the rally.
The decline in oil over the last week is a key factor taking Fed hikes off the table.