Alphabet Inc. granted Sundar Pichai, chief executive of the company’s main Google business, an equity award valued at nearly $200 million, making him one of the world’s highest-paid executives. In a securities filing Friday, Alphabet said it awarded Mr. Pichai 273,328 Class C Google stock units on Feb. 3. At that time, the grant was valued at $199 million, though subsequent declines in Alphabet shares put the current value at about $182 million. The new award vests in quarterly increments over the next four years as long as Mr. Pichai is employed by Alphabet.