Does Carl Icahn's tweets make or break Apple Inc. (NASDAQ:AAPL) market cap?

How powerful are his tweets over Apple Inc.'s market cap?

Back in Aug., Icahn posted in Twitter his assumption that Apple at $470 was "extremely undervalued." He also announced that he already hold a "large position" in the company.

We currently have a large position in APPLE. We believe the company to be extremely undervalued. Spoke to Tim Cook today. More to come.

— Carl Icahn (@Carl_C_Icahn) Aug. 13, 2013

Within just minutes of interval, he posted again that he had a nice "talk" with Apple CEO Tim Cook about accelerating Apple's targeted $60-billion buyback program and hinted that there will be more talks like this in the future.

Had a nice conversation with Tim Cook today. Discussed my opinion that a larger buyback should be done now. We plan to speak again shortly. — Carl Icahn (@Carl_C_Icahn) Aug. 13, 2013

In an article from Fortune in Aug., Philip Elmer-Dewitt reported that Apple's share at $475.77 gained a $9 increase within just three minutes of interval, simultaneously with Icahn's tweets. According to Dewitt, who had been keeping track of Apple's share, the $9 surge in less than three minutes was already a gain in market value of $17 billion in just over an hour.

"On the strength of two tweets from Icahn, the stock soared and the company gained $17 billion in market value in just over an hour," Dewitt noted.

By Aug. 23 Icahn posted that he will be meeting with Cook again on Sept.

Spoke to Tim. Planning dinner in September. Tim believes in buyback and is doing one. What will be discussed is magnitude.

— Carl Icahn (@Carl_C_Icahn) Aug. 22, 2013

Around this time up until the meeting with Cook, Icahn was very visible with his media interviews saying that he was prodding Apple to accelerate and increase its $60 billion buyback program. As of Sept. 25, 2013, 11:45pm (EDT), Apple Inc. (NASDAQ:AAPL) stock quote is at $481.53 as quoted by NASDAQ OMX group Inc based on *delayed chart. Apple Inc. (NASDAQ:AAPL) stocks recommendation is at "Strong Buy." As all this happens, Analyst Ratings Network reported some unusual options trading activity with Apple (NASDAQ:AAPL). According to the report, investors acquired 91,793 put options on Apple (NASDAQ:AAPL) - a representation of a 680 percent increase in comparison to the typical volume of 11,761 put options. Analyst Ratings network also reported that Apple (NASDAQ:AAPL traded up at 0.97, hitting 486.22, with a trading volume of 8, 447,781 shares. The company has a 52 week low of $385.10 and a 52 week high of $682.17. Apple's stock had a 50-day moving average of $484.3 and its 200-day moving average is $446.7, with a market cap of $441.7 billion and a P/E ratio of 12.01.

The rumour continued to circulate as another tweet from Icahn on Oct. 1 hinted a $150 billion buyback program.

Had a cordial dinner with Tim last night. We pushed hard for a 150 billion buyback. We decided to continue dialogue in about three weeks. — Carl Icahn (@Carl_C_Icahn) Oct. 1, 2013

After Icahn's tweet on Oct. 1, as there were no confirmation that Apple indeed agreed to the buyback and that dialogue has to happen again in three weeks, there had been a slight decrease with Apple's share.

As of Oct. 4, Friday, based on a real time data published by NASDAQ OMX, Apple stock quote is at $483, with a 1.33 percent decrease.