Jan 4 (Reuters) - Martin Sorrell's S4 Capital said on Monday it had acquired two U.S.-based businesses for an undisclosed sum, as it moves faster to implement its revamped all-digital advertising strategy in Europe and elsewhere following Brexit.

The digital advertising and marketing services firm, which has been sealing deals for content on Facebook and Alphabet Inc's Google, said it would combine U.S.-based Decoded Advertising with its MediaMonks unit and Metric Theory with its MightyHive business.

Sorrell has been building up S4 following his departure from ad giant WPP, and the two new deals are the latest to form a purely digital global advertising firm as the company stays in pursuit of red-hot digital growth.

Media agency Decoded Advertising services global clients such as T-Mobile, Visa and Intuit, while San Francisco-based Metric Theory provides services across search, social media and commerce media.

"Both combinations continue our momentum, broadening our digital, strategic, creative, data & digital media capabilities in line with our objectives for 2021," Sorrell said in a statement.

S4 also said its performance in the first 11 months of 2020 and expectations for December were in line with the market view. (Reporting by Yadarisa Shabong in Bengaluru; Editing by Shailesh Kuber and Ramakrishnan M.)