Martin Sorrell's S4 Capital buys programmatic ad firm MightyHive

LONDON, Dec 4 (Reuters) - Martin Sorrell's S4 Capital has agreed to buy San Francisco-based programmatic ad firm MightyHive for an enterprise value of $150 million, funded by the issue of new shares worth 74 million pounds ($94 million).

Sorrell said the deal marked an important second strategic step for his new company. "The peanut has now morphed into a coconut, and is growing and ripening," he said on Tuesday.

($1 = 0.7850 pounds) (Reporting by Paul Sandle; editing by Kate Holton)