NEW YORK ( TheStreet) -- The meme du jour is the latest missive from Jeremy Grantham, who 32 years ago co-founded Boston-based asset manager GMO. In his letter to shareholders, there was a bit about being anti-China but pro-emerging markets. That concern was heaped on fears about the world's most populous nation. Lending has skyrocketed, fueling talk of bubble trouble. On Wednesday, the Chinese stock market dove 5%. My initial reaction: I'm not sure how a market that's still down almost 50% from its peak can be a bubble. (Though it is up more than 80% off the low.) Trying to rationalize where there is no bubble would seem to be counter-productive and herald poor risk management. I've been a huge believer in China as an investment destination for many years. There's no question in my mind that China is on the path to playing a much larger role in the world economic order. But you can't own it blindly or in the form of a lopsided bet that could have a ruinous effect on a portfolio and, thus, a financial plan. What we've learned this decade is that no investment theme is impervious to panic declines, slow-moving declines or any other sort of derailment. During this bear market, the Shanghai Composite Index fell from 6,100 to 1,800, the Hang Seng Index dropped from 31,000 to 11,000 and the Hang Seng Enterprises Index declined from 20,000 to 5,600. All three have come roaring back but are still a long way from their high-water marks.