Well, this is interesting….why the difference?
https://www.google.com/search?q=PACIFIC+WESTERN+BANK+SHARES
https://www.marketwatch.com/investing/stock/pacw
I was a little off in my explanation. The first pic from Market Watch includes after-hours trading. But the question of why is the Google search as I used the exact same phrase as OP. You're probably right, different feeds but since it's Google I'm not giving them any benefit.
related:
https://www.marketwatch.com/story/pacwest-stock-plummets-more-than-50-after-report-of-potential-sale-other-bank-stocks-join-in-decline-dbb89ee