I've been following the Intrade Senate Odds. It's interesting to watch the changes as new information comes available.
I'm going to try to write a series of these as we head to November to catch the changes in investor sentiment between now and November.
Methodology: I'm only interested in watching the races that are competitive. Many of the races really have no market because one candidate is a prohibitive favorite. I'm also not going to be looking at any race where the normalized probability of one candidate winning is > 80%. Normalized probability means that I'll be the 2 highest candidates and treating them like their probabilities add to 100%.
Florida: Nelson (D) leads Mack (R), 55.3 - 44.7. This one has been stable for a while. Democratic hold.
Indiana: Mourdock (R) leads Donnelly(D), 65.0 - 35.0. Donnelly has been slowly closing the gap. Republican hold.
Massachusetts: Warren(D) has had a surprisingly steady lead over Brown(R), 52.6 - 47.4. It will be interesting to see if she keeps it as a bad poll is out recently. One other note: The trading volume on this race is much higher than most. It's obvious that it has national attention. Democratic Pickup.
Missouri: McCaskill(D) switched around the probabilities this week to 61.5 - 39.5. Until this week she was trailing badly, but Akin (R) has been legitimately raped on the Intrade odds. Democratic Hold.
Montana: Tester(D) hasn't fared well on Intrade as Rehberg has held a consistent lead. Republican Pickup.
Nebraska: Bob Kerrey (D) just hasn't caught on in Nebraska. Deb Fischer (R) defied pre primary expectations and has held her lead 79.0% - 21%. Republican Pickup.
Nevada: Heller (R) over Berkley (D), 79.1% - 20.1%. One problem with this prediction -- this is an extremely thinly traded race, even a few hundred dollars could swing these percentages and close most of the gap. Republican Hold.
North Dakota: Berg (R) holding on strong over Heitkamp (D), 79.1% - 20.1%. Another thinly traded race. I keep thinking that Heitkamp will close part of the gap, but it hasn't happened yet.Republican Pickup.
Ohio: Brown (D) holding strong, 57.8% - 42.2%. Mandel (R) made a run a few weeks ago and actually went a little ahead, but has fallen back.Democratic Hold.
Virginia: Allen (R) over Kaine (D), 55.3% - 44.7%. This one was tied just a few weeks ago, but Allen has pulled ahead. Republican Pickup.
Wisconsin: Thompson(R) over Baldwin(D), 71.4% - 28.6%. Thompson has picked up ground since the primary. He was probably the Republican's best.Republican Pickup.
Off the Board (Probability over 80%):
Arizona (R Hold)
California (D Hold)
Connecticut (D Pickup from I)
Delaware (D Hold)
Hawaii (D Hold)
Maine (I Pickup from R)
Maryland (D Hold)
Michigan (D Hold)
Minnesota (D Hold)
Mississippi (R Hold)
New Jersey (D Hold)
New Mexico (D Hold)
New York (D Hold)
Pennsylvania (D Hold)
Rhode Island (D Hold)
Tennessee (R Hold)
Texas (R Hold)
Utah (R Hold)
Vermont (I Hold)
Washington (R Hold)
West Virginia (D Hold)
So the current Intrade tally is 5 Republican pickups (Montana, Nebraska, North Dakota, Virginia, and Wisconsin with 1 Democratic pickup (Massachusetts) and an Independent pickup (Maine).
Final Tally -- 50 Republicans, 48 Democrats, 2 Independent (Sanders (VT) caucusing with Democrats, probably King (ME) also.
[Updated to fix grammar issues]