Owing to severe decline in monthly page visits, from 8.5 billion to 4.7 billion in the last two years, Facebook is set to cede its long-held second position among the top websites in the US to YouTube, according to a new study.

Although Facebook's app traffic has grown, it is not enough to make up for that loss, CNBC reported on Wednesday citing the study by market research firm SimilarWeb.

Facebook earlier reported that in the second quarter of this year, its number of daily active users remained flat in North America and went down in Europe.

Owned by Google parent Alphabet, YouTube, on the other hand, has seen increased traffic and rise in viewership, said the study that found Google's position as the biggest website in the US remaining unshaken.

The researchers projects that Amazon is set to overtake Yahoo as the fourth most-visited website in the US in the next couple of months.