According to the Case-Shiller Index, home price declines have been slowing for the past few months. There are those who think this could be a sign of home prices approaching a "bottom".  According to CNBC:

Among the strongest signs that the the hard-hit sector could be recovering, home prices in many regions of the country are now falling at a slower rate, after two years of declines, and in some areas prices have actually risen.

Seeking Alpha also gives this moderation as a positive sign:

Clearly, the May Case-Schiller report is nothing to pop the champagne over, but it shows the market’s capacity to change. The rate of month to month decline in home prices has decelerated in the last three months reported. It began with a 2.7% decline in February (the peak month-to-month drop in prices to date), slowing to declines of 2.1%, 1.3%, and 0.9% in March, April and May, respectively. Two regions showed month to month increases in March, growing to seven regions in May. With the rate of decline dropping lower by the month, if this trend continues, home prices will start to rise within the next few months. It would certainly be too optimistic to say that this is actually the beginning of a bottom, but it is sure starting to look like one.

I, for one, say that the moderation of the past few months is not indicative of a market bottom, but merely shows a typical seasonal pattern. Here’s why:

Prices, like home sales, are affected by the season.  Traditionally, month-to-month home price appreciation has been greater in the summer and smaller in the winter.  Even in bad years, summer demand is higher, putting more upward pressure on prices during the season.

To demonstrate this, I took the data for the "10 City Composite" of the Case-Shiller Index and calculated the month-to-month appreciation from 1987 to the present. [I used the "10 City" as opposed to the "20 City", as the "20 City" data only goes back to 2000.] Then I averaged the month-to-month appreciation for each month of the year.  Here’s what the graph looks like:

It stands to reason that if price increases are greater in the summer in an appreciating market, then price decreases will be smaller in the summer in a declining market.

Year-over-year remains the more important measure. Summer "moderation" is nothing to get worked up about. Should price declines continue to moderate after the usual June peak, I think we might be able to attach some significance to it.  In the meantime, I think that "bottom" in home prices remains some distance away.