Amazon's Its online advertising business brought in $14.3 billion in the third quarter, up 19% from a year earlier, in line with analyst estimates of $14.3 billion.

The Seattle tech giant announced the financial results of its growing advertising unit on Thursday as part of its latest earnings report. Amazon's total third-quarter revenue was $158.9 billion, beating analyst estimates of $157.2 billion.

Amazon's online advertising business still represents a fraction of the company's overall business, but its growth over the years has made it a key competitor alphabet And Metawho lead the digital advertising market. Alphabet's Google currently represents 27.7% of the global digital advertising market, followed by Meta at 22.8% and Amazon at 8.8%, according to data Emarketer provided to CNBC.

Meta's third-quarter advertising revenue was $39.9 billion, up 19% year-over-year. According to StreetAccount, that was slightly above analysts' expectations of $39.49 billion. Ads accounted for 98.3% of Meta's total revenue in the third quarter.

Alphabet generated $65.85 billion in advertising revenue in the third quarter, the company reported Tuesday. That was up 10% from $59.65 billion a year earlier. Additionally, advertising revenue for the company's YouTube unit increased 12% year-over-year to $8.92 billion.