Question: Why do pork bellies get tumbled?
About the article "Bacon", section "Process".

Candidate passages:
  "They Don't Get Paid, They Don't Get Laid, but Boy Do They Work Hard!"
compilation album (1989)  "Very Small World" compilation album (1991)  "Can of Pork" compilation album (1992)  "Later That Same Year" - "My City"  
  "Can of Pork" - "North Berkeley"  "Very Small World" - "New Regulations"  "They Don't Get Paid, They Don't Get Laid, But Boy Do They Work Hard!"
- "Long Way to Go"  "Later That Same Year" - "My City"  
 futures.
The pork belly futures contract became an icon of futures and commodities trading, frequently used as a placeholder name for commodities in general and appearing in several depictions of the field in popular media (such as the 1974 movie "For Pete's Sake" and the 1983 movie "Trading Places").
Inaugurated in 1961 on the Chicago Mercantile Exchange (CME), frozen pork belly futures were developed as a risk management device to meet the needs of meat packers who processed pork and had to contend with volatile hog prices, as well as price risks on processed products held in inventory.
The futures contracts were useful in guiding inventories and establishing forward pricing.
The unit of trading was 20 short tons () of frozen, trimmed bellies.
(Bellies typically weigh around .)
Pork bellies can be kept in cold storage for an extended period of time, and generally it was the frozen bellies that were most actively traded.
Spot prices vary depending on the amount of inventory in cold storage and the seasonal demand for bacon as well as the origin of the pork; in the past, the former drove the prices of the futures as well.
In more recent years pork belly futures' prominence declined; eventually they were among the least-traded contracts on the CME, and were delisted for trading on July 18, 2011. 
Agricultural Commodity Contracts include: Live Cattle, Lean Hogs, Feeder Cattle, Class IV Milk, Class III Milk, Frozen Pork Bellies, International Skimmed Milk Powder (ISM), Nonfat Dry Milk, Deliverable Nonfat Dry Milk, Dry Whey, Cash-Settled Butter, Butter, Random Length Lumber, Softwood Pulp, Hardwood Pulp. 
Pork belly is a boneless cut of fatty meat from the belly of a pig.
Pork belly is popular in Asian cuisine, including the Rafute of Okinawan cuisine, and forms a part of many traditional European dishes such as the Alsatian "Choucroute garnie", the Swiss "", and the German "Schlachtplatte".
In the United States, bacon is most often made from pork bellies.
In Colombian cuisine pork belly strips are fried and served as part of bandeja paisa (chicharon).
A 100-gram serving of pork belly typically has about 520 calories.
The calorie breakdown is: 92% fat (53 g), 0% (0 g) carbohydrates, and 8% (9 g) protein.
This cut of meat is enormously popular in Chinese cuisine and Korean cuisine.
In Chinese cuisine, it is usually diced, browned then slowly braised with skin on, or sometimes marinated and cooked as a whole slab.
Pork belly is used to make Slowly Braised Pork Belly (紅燒肉) or "Dongpo pork" (東坡肉) in China (Sweet and Sour Pork is made with pork fillet).
Koreans cook "Samgyeopsal" on a grill with garlic, often accompanied by "soju".
Uncured whole pork belly is a popular dish in American cuisine as well.