Seventeen of 21 Japanese biotechs ended last year up 10% or more, and 20 are up more than 25% thus far in 2013. Notably, share prices for DNA Chip Research Inc. (Tokyo:2397) and NanoCarrier Co. Ltd. (Tokyo:4571) have already doubled this year, though there are signs the momentum is ebbing. Nearly all 21 stocks had their 52-week highs in January, and last week the equal price-weighted index of the biotechs slipped 8%.

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