Tech stocks boom, but some stock pickers are wary

San Francisco

TECHNOLOGY stocks had another scorching weeklong run last month, capped off by Amazon's startling decision to buy Whole Foods for US$13.4 billion. And like many stock pickers these days, the portfolio managers at Parnassus Investments, a mutual fund company that invests mostly in large American companies, were at their wits' end as they gathered for the firm's weekly investment committee meeting.

"These stocks are hitting highs - again," said Todd C Ahlsten, who oversees the firm's US$15.6 billion core equity fund, pointing out that even low-risk exchange-traded funds were piling into the likes of Facebook, Apple, Google, Netflix and, yes, Amazon.