Explain the concept of Merger and Acquisition and its impact on stock prices in Saudi Arabia? Merger and acquisition (M&A) can have a great effect on stock prices. After the announcement of M&A deal stock prices tend to move in both directions. An increase in value for the target company and a decrease in value for the acquiring company. A great example of this phenomena is the recent M&A of the two Saudi banks SAAB and Alawwal.