Shares of the iPad and iPhone maker eclipsed the $600 barrier for the first time on Thursday, only about a month after topping the $500 mark for the first time.

Just a day before Apple’s new iPad becomes available in stores the stock ticked up to $600.01 at Thursday’s open before selling off. The new iPad, at a starting retail price of $499, is cheap compared with one share of stock. 

Apple Inc’s rally has been stunning — the stock is up 47 percent for the year and nearly 10 percent for the month.

“There is buyers’ panic out there. What kind of a right-minded person would buy this after looking at an Apple chart that has been basically up in a straight line?” said James Dailey, portfolio manager at TEAM Asset Strategy Fund in Harrisburg, Pennsylvania. Dailey owns put options in Apple as a hedging tool because the stock is “too hot to short.”

Last month, the company became only the sixth company in US history to top $500 billion in market capitalization, a significant move for a company whose stock traded at $10 about a

decade ago. None of the others, which include Exxon Mobil and Microsoft, were able to sustain that market value over time.  

“The frenzy gets compounded because the Apple has become dominant in indexes. They need to have Apple in their portfolios and they don’t want to miss the train that is leaving the station,” Dailey said.

Apple currently makes up about 18.5 percent of the Nasdaq 100 stock index. It was cut to 12.3 percent from 20.5 percent in April 2011, but a surge in price has pushed the stock back up, making this index of 100 well-known companies hostage to the performance of a few technology titans like Apple.

Dailey, comparing Apple to tech stocks during the tech bubble and a sudden surge in silver prices last year, said he expects a 15-20 percent correction in Apple stock in the next couple of months, if not weeks.

Earlier this week, Morgan Stanley and Canaccord Genuity both lifted their price targets on the stock to above $700.

Coincidentally, on the same day Apple touched $600, the S&P 500 topped 1,400 for the first time since June 2008 on Thursday.

Apple was trading down 0.7 percent at around $585 per share in early afternoon trading.

One out of every five stock options trades in Wednesday’s options market was in Apple, according to Henry Schwartz, president of options analytics firm Trade Alert. Options trading

volume hit a record 2.11 million contracts on Wednesday, according to Trade Alert.  

“It’s also the greatest non-dividend single stock option volume seen since Citigroup was in the $4 pre-reverse split range in early 2011,” Schwartz said.

Volatility in the stock has increased, judging by a VIX index that tracks Apple options. Didn’t know Apple had its own VIX? It does — as do other blue-chip companies like IBM. Apple’s

VIX was introduced in January 2011.

The CBOE Apple VIX index, which measures the expected 30-day volatility of the underlying shares of Apple, jumped 13.1 percent on Thursday to 42.12. The index is up 22 percent for the month, suggesting more gyrations ahead as more investors speculate on further short-term gains.

“What it shows is how crazy things have been getting recently in Apple,” said Dan Nathan, a founder of RiskReversal.com. 

The CBOE Apple VIX index works a lot like the CBOE Volatility index which generally moves inversely to the S&P 500. But while the VIX has declined dramatically to multi-year lows as the market makes new highs, Apple’s volatility index has been rising in lockstep with the stock price appreciation.

“Volatility going higher as a stock goes higher is not usual activity and tends to happen in bubble situations. Is Apple a one-man bubble?” Nathan said.