Google parent Alphabet on Tuesday reported that its quarterly profit rocketed some 50 percent to $15.2 billion at the end of last year as its digital ad business thrived. Alphabet revenue in the final three months of last year hit nearly $57 billion, compared with $46 billion in the same period in 2019, according to the internet titan. The strong quarter "was driven by Search and YouTube, as consumer and business activity recovered from earlier in the year," Alphabet chief financial officer Ruth Porat said in the earnings release. gc/st