Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of network-chip designer Inphi (Nasdaq: IPHI) jumped as much as 10.2% today on rather ordinary trading volume.

So what: The only news on Inphi today comes from a penny-stock newsletter that pumps this small-cap to high heavens -- but the volume spike one would expect from a successful pump-and-dump scheme isn't there. On the other hand, chip stocks are up in general today and quasi-competitor Sigma Designs (Nasdaq: SIGM) just reported earnings.

Now what: Sigma's report sent that stock down to the basement for a thorough flogging -- perhaps investors are reading market share gains for Inphi in Sigma's tea leaves. Or perhaps that penny-stock presentation made a mark on the market after all. Either way, this recent IPO is subject to wild swings until further notice, and as likely to jump again tomorrow as it is to crash and burn. None of this is Inphi's own fault, but serious investors would do best to let this hot potato cool down a bit before letting it touch your portfolio.

Interested in more info on Inphi? Add it to your watchlist.

Fool contributor Anders Bylund holds no position in any of the companies discussed here. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool is investors writing for investors.