It's been a busy week on Wall Street, and there's plenty of news to catch up on if you missed it. So sit back, relax, and soak it in Fool-style.

1. The Thai coup: echoes of an earlier crisis?
What happened? While visiting New York City for a United Nations General Assembly meeting, Thai Prime Minister Thaksin Shinawatra was ousted in a bloodless coup lead by the military in his home country. For the time being, the nation will remain under control of the Chief of the Army. New elections may be delayed for some time.

What does it mean for your portfolio? There are significant allegations of corruption against the deposed prime minister and his government, but he has brought some stability as well. The less-stable junta hopefully will not be a permanent substitution. There's something important to draw from this: Historically, Thailand has displayed an ability to affect the rest of the Asian economic climate. Remember the Asian crisis of 1997? Well, one source of that little debacle was a speculative attack on the Thai currency, the baht. Its value crashed, and that led to a myriad of other financial happenings. Those with investments in the Far East should be especially mindful of the events which are bound to unfold.

2. Schwarzenegger and friends attempt to terminate emissions
What happened? This past week, the state of California initiated a lawsuit against six major automakers, alleging that they have directly contributed to environmental damage as a result of emissions from vehicles.

What does it mean for your portfolio? We may be years away from an actual reduction in the amount of greenhouse gases that we release into the atmosphere. This lawsuit seems to be a first step toward combating them. California Attorney General Bill Lockyear believes that this action will penalize carmakers such as General Motors (NYSE:GM) and Toyota (NYSE:TM) to the tune of hundreds of millions of dollars. This precedent-setting case might make investors cringe, but don't sell out quite yet. A similar suit was filed in New York and promptly thrown out. Long-term: Bet on companies like Honda that plan to steal market share in a greener future.

3. Bernanke stays the course
What happened? The Fed has maintained its current level of 5.25% interest on borrowing for the second straight month.

What does it mean for your portfolio? The powers that be have a difficult job balancing pressures from inflation, which have been significant for the past few months, and impending concerns over an economic recession. An improper change in the interest rate could tilt the scale in either direction, prompting all sorts of fiscal undesirables. But fears stemming from inflation seem to be quelled for the time being, largely thanks to a drop in energy prices. However, they are not completely gone. Current thinking from economists suggests that rates will stay static for October's meeting and perhaps longer into the future.

4. Yahoo! wobbles on decreased ad revenue, others imitate
What happened? A large group of Internet companies, including Amazon (NASDAQ:AMZN), Google (NASDAQ:GOOG), and others, fell on Tuesday when Yahoo! (NASDAQ:YHOO) reported that revenues streaming from advertisements were expected to be lower than previously thought.

What does it mean for your portfolio? The monetary fates of Internet companies are seemingly interconnected. With Yahoo!'s announcement came the battering of others like Google, but, similarly, fresh synergies are on the horizon for the likes of Yahoo!, which might prompt a resurgence. On Thursday, it was revealed that Yahoo! is in "serious" talks with social-networking site Facebook for a potential buyout in the ballpark of $1 billion. Many believe that this acquisition might position the company well in the future, but watch for an overpay situation. History is fraught with companies that paid too much and got too little in return.

5. Amaranth has got some 'splaining to do
What happened? Amaranth, a hedge fund out of Greenwich, Conn., apparently has done very little hedging, after announcing losses of nearly $6 billion this month.

What does it mean for your portfolio? This is not the first levered company to suffer such a severe collapse, nor will it be the last. But it might just ground the inflated status of this unregulated financial industry. Over the course of one month, Amaranth has lost 65% of assets, down from approximately $9.5 billion, all under the leadership of a 32-year-old natural gas trader! Although no questions suggesting impropriety have surfaced as of yet, it remains clear that these record-sized funds are subject to the same incompetence and foolishness - lower-case f -- that exists all around the investment marketplace.

6. Energy prices continue to slide
What happened? As suggested by yours truly at the beginning of September, oil and gas prices have continued their descent into the colder months. Since the middle of August, the price of November futures for light crude oil has fallen roughly 22% to around $60.

What does it mean for your portfolio? As we near October practically hurricane-free, energy prices are continuing to react to large surpluses and slowly recovering refinery capacity. More recently, however, international rebels Hugo Chavez of Venezuela and Mahmoud Ahmadinejad of Iran have unofficially announced their intentions to make life difficult for the United States. The two nations aren't the biggest suppliers to the U.S., but together they can exercise a good degree of influence over international prices. However, though they might be able, there isn't enough evidence to suggest that either one of these troublemakers will stop the decline of gas prices.

7. Wal-Mart undercuts competition . again
What happened? Ladies and gentlemen, Wal-Mart (NYSE:WMT) has done it again. The international megastore has recently announced its intentions to sell prescription drugs at a massive discount to competitors in the state of Florida.

What does it mean for your portfolio? Though the program has been initiated in senior-centric Florida, the company plans to rapidly expand the cost-cutting across the nation. Competitors like CVS (NYSE:CVS) and Walgreen will be forced into a tight spot as a result of this move, and have suffered on the market as a result. Prices for both companies fell by more than $3 a share on Thursday. The drugs included in the program are some of the most popular on the market today, and will be sold at discounts of anywhere from 16% to 66% to competitors' prices. Seemingly, this is just more of the same from the Walton family.

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Fool contributor Nick Kapur owns shares of Wal-Mart, which is a Motley Fool Inside Value recommendation. Amazon and Yahoo! are Motley Fool Stock Advisor picks. The Motley Fool has a disclosure policy.