Intel Corp smashed quarterly earnings expectations and declared that the worst may be over for the tech sector, but its shares slid 4.5 percent after it failed to give a clear revenue forecast.

The world's top chipmaker said on Tuesday it believed personal computer sales hit a trough in the first quarter but there was still too much market and economic uncertainty to give a precise projection for the second quarter.

Intel said -- for internal planning purposes -- it was planning for revenue to come in flat after the first quarter's $7.1 billion, compared with analysts' average estimate of $7 billion.

Shares of the chip giant, a bellwether for the market and the global tech industry, wended their way south, dragging down S&P 500 and Nasdaq 100 stock index futures.

Before Tuesday's after-hours drop to $15.29 from a close of $16.01, Intel stock had leapt 32 percent from a 2009 nadir of $12.01. That rise was nearly twice the Nasdaq's gain of 17 percent over the same period.

I would have liked to see higher gross margin guidance, said Edward Jones analyst Bill Kreher. The stock has had a heck of the run in recent weeks, so it may be time for a breather here given that visibility does remain limited.

Gross margins, a closely watched barometer for the company, came to 45.6 percent in the first quarter -- just a whisker above Wall Street's forecast of 43.5 percent. For the second quarter, the company expects margins to remain in the mid-40s.

Intel, which controls roughly 80 percent of the global microprocessor market, is closely watched as a barometer of overall IT industry health.

It reported a net profit in the first quarter ended March 28 of $647 million, or 11 cents a share, down 55 percent from $1.44 billion, or 25 cents a share, a year earlier.

Analysts had expected a much lower profit of 3 cents a share, according to Reuters Estimates.

The numbers were good but people were expecting stronger commentary. Instead, we got flattish expectations, said Avi Cohen, managing partner of Avian Securities.

The shares are down because people were disappointed with the lack of specific guidance. People knew it was going to be north of $7 billion but they wanted to know how much Intel was willing to commit to the next quarter.

Investors have been bullish on the chip sector of late and shares of semiconductor companies have gone on a tear. The Philadelphia Semiconductor Index is up roughly 30 percent since late February.

But industry executives, still shaken by one of the sector's worst downturns ever, argue that too much uncertainty remains for the future.

Also on Tuesday, fellow chip industry player Linear Technology said forecasting operating results in the current environment was difficult.

We did see signs that the PC market bottomed out in the first quarter, said Chief Financial Officer Stacy Smith.

But there still is a lot of economic uncertainty out there that creates a wider range of potential outcomes than normal.

Intel's revenue fell 26 percent to $7.1 billion in the reporting period, versus the average analyst estimate of $6.98 billion.

Shares of Santa Clara, California-based Intel had risen 3 cents to close at $16.01 on Nasdaq on Tuesday, but fell to $15.29 in extended trade.

(Editing by Edwin Chan, editing by Matthew Lewis)

Intel Fall