The acquisition of Urstadt Biddle Properties by Regency Centers is a significant event for both companies. However, the short-term impact on Regency Centers' stock price is uncertain, as the market may react positively to the expansion or negatively to the cost of the acquisition.

Urstadt Biddle Properties' shareholders are likely to benefit from the all-stock acquisition by Regency Centers, as they will receive shares in the larger, more diversified company. This could lead to a short-term increase in Urstadt Biddle Properties' stock price.