Jo Cox memorial
Human rights campaigner Malala Yousafzai delivers a speech on stage at Trafalgar Square during late MP Jo Cox's memorialDan Kitwood/Getty Images

Malala Yousafzai, who rose to global fame after the Taliban shot her for speaking out against extremism in Pakistan, and her family have become millionaires in the span of four years through the sales of her memoir and international speech arrangements.

The youngest to win the Nobel peace prize, Yousafzai's best-selling book, I Am Malala, which was published in 2013, has sold at least 1.8 million copies worldwide with 287,170 copies in Britain alone. The book fetched the 18-year-old about £2.2m ($3m). Her autobiography documents her experience of growing up under Taliban rule.

Besides, the activist reportedly makes $152,000 (£ 113,523) per speech, which is said to be one of the highest figures among Nobel laureates, according to US-based Institute for Policy Studies.

"Since the publication of Malala's book, Malala and her family have donated more than $1m to charities, mostly for education-focused projects across the world including Pakistan," Yousafzai's family told the Thomson Reuters Foundation via an email statement.

Yousafzai's trust Malala Fund raises money to support educational projects for girls from developing countries. A company set up by her parents had a net worth of £1.87m as of August 2015, an increase of nearly 65% from 2014. Salarzai Ltd was set up to protect the rights to Yousafzai's life account.

The Pakistani teenage activist lives with her family in Birmingham ever since she came to the UK to receive medical treatment. She was fatally attacked by Taliban in an assassination attempt when she was in her school bus in Pakistan's Swat Valley in October 2012. Yousafzai was constantly in the news prior to the attack too by actively campaigning for young women's rights and education. She went on to write a blog for the BBC Urdu website.

During a conference in London earlier this year, she urged world leaders to raise $1.4b to provide aid for educating Syrian refugee children.