NEW YORK (CNN/Money) - The selloff in Treasurys has begun wearing at investors' nerves. Particularly investors who are heavily invested in tech.

In just two months, the yield on the 10-year Treasury note has jumped from a 45-year low of 3.11 percent all the way up to 4.6 percent, its highest level in over a year. While equity types weren't terribly concerned about what was happening in the Treasury pit at first -- if anything they showed a touch of schadenfreude at seeing the bond guys take some lumps -- the selloff has become so relentless that it is now the stock market's number-one worry.

Justin Lahart, senior writer at CNN/Money, talks about the rise in bond yields that is raising red flags for tech investors. Play video (Real or Windows Media)

The Treasury selloff, after all, doesn't do the economy a lick of good. With the backup in yields there has also been a backup in mortgage rates. As a result mortgage activity has fallen back to year-ago levels and much of the juice consumers have been using to keep the economy going has been taken away. Most economists reckon that the economy still has the wherewithal to recover, but they also warn that it has become more vulnerable to shock.

But for tech in particular, the bond selloff raises other concerns.

First off, tech valuations are quite steep -- tech stocks in the S&P 500 trade at 27.5 times expected earnings over the next year. Profits will have to grow quite quickly to justify these valuations and, meantime, the big rise in yields is beginning to make Treasurys look more attractive. Credit Suisse First Boston strategist Paddy Jilek (who correctly forecast late last year that tech spending would come back) cited the rise in Treasury yields when he recommended on Wednesday that clients lower tech stocks in their portfolios from overweight to neutral.

The runup in Treasury yields may also make it harder for tech companies to make the sorts of profits Wall Street expects. How so? Rising Treasury yields translate into higher yields on corporate debt. As a result, companies aren't able to raise as much cash in the bond market. That, in turn, means that they aren't able spend as much money on new tech equipment.