https://www.theverge.com/2019/1/2/18165804/apple-iphone-sales-weak-demand-tim-cook-letter-revised-q1-estimate > Apple CEO Tim Cook published a letter to investors today warning of weaker than expected first-quarter earnings, citing “fewer iPhone upgrades than we had anticipated.” The weakened demand came primarily from China, although Cook notes that “in some developed markets, iPhone upgrades also were not as strong as we thought they would be.”