آیا قیمت ها بصورت آنلاین"چسبنده" اند؟ اثر ساختار بازار و واکنش های نامتقارن به شوک های هزینه ای در بازار وام مسکن آنلاین

We analyze daily mortgage rates posted by online lenders at the price comparison site, Microsurf. While cost shocks occurred almost daily in our sample, quoted mortgage rates are surprisingly rigid: Only 16% of the posted rates represent changes. However, firms that adjusted rates in response to cost shocks did so quite rapidly; about 98% of a cost shock was passed through within 2 days of the cost shock. Duration analysis reveals that the observed rigidity in rates systematically depends on market structure: Online mortgage rates are 30% to 40% more durable in concentrated markets than in markets where there are many competitors. We also find that rates posted online tend to exhibit downward stickiness; rate adjustments in response to cost increases are about twice the corresponding adjustments for cost decreases.

Economists comparing the competitiveness of electronic and traditional market environments often argue that electronic commerce entails lower transaction costs. On the demand side, the cost to consumers of becoming informed in e-retail settings is low due to readily available online information and superior search capabilities.2 These lower transaction costs and the globalization of markets may enhance competition and result in prices that more closely match the external economic environment. On the other hand, the fact that these new technologies permit firms to monitor rival's prices and to adjust prices in real time may lead to higher prices due to collusion.3 While a number of papers have documented that the Internet has yet to eliminate price dispersion (see Bakos (2001) and Smith et al. (2000) for surveys, and Baye et al. (2004) for an analysis of the impact of market structure on price dispersion), relatively little is known about the economic forces that induce firms competing in online markets to adjust their prices. Since it is arguably easier for firms to change online prices than to change price tags at brick-and-mortar outlets, one might expect prices posted in online markets to change very frequently in response to changes in marginal cost and other economic factors. To examine price adjustment patterns in online markets, we assembled firm-level panel data consisting of daily observations on the rates charged by different online lenders for 30-year fixed-rate mortgages. The data were obtained from Microsurf, which is a price comparison site for mortgages. Mortgage providers submit their mortgage rate quotes, and terms and conditions for loan origination to Microsurf in real time. Microsurf publishes these rates along with other characteristics of loans and lenders on its web site, and consumers may access this information free of charge. The data, which consist of firms' pricing decisions over the period April 30, 1998 through July 22, 1998, reveal considerable price dispersion. The range in interest rates charged – the difference between the maximum and minimum rate – exceeds 0.25 on all but one date in the sample. These price differences are not transient in nature—they are observed over time and do not “converge” to zero during the sample period. In short, dispersion in mortgage rates appears to be an equilibrium phenomenon among online lenders. As we discuss in the next section, these observations are consistent with a variety of theoretical models of online price dispersion, as well as levels of dispersion documented in online markets for books and electronic products. 4 Since the persistence of price dispersion in online markets is well-documented in the recent literature, our aim in the present paper is to identify factors that influence firms to adjust their prices. This focus is motivated, in part, by the considerable variation observed in online lenders' decisions to adjust the mortgage rates posted at Microsurf. For instance, based on daily rates for 30-year fixed-rate mortgages listed at Microsurf over the 3-month sample period, one lender (Universal Mortgage) never changed its posted rate, while another lender (Custom Mortgage) changed its rate about 70% of the time. Over the period, the 10-year T-Bond rate (a commonly used proxy for lenders' marginal cost of funds 5) changed on over 87% of the days. In Section 2 we show that a variety of different theoretical models predict that the frequency with which firms adjust their prices depends on structural variables, such as the number of competing firms, characteristics of the product, the frequency of cost changes, and the menu cost of adjusting prices. In Section 3 we describe our data and explain why it is well-suited for an econometric analysis of the determinants of firms' decisions to adjust the prices posted on the Internet. Section 4 presents the results of our data analysis. The econometric analysis reveals that market structure is a critical determinant of the frequency with which online lenders adjust their rates: Rates are adjusted more frequently in markets with a large number of competitors and less frequently in markets where competition is less intense. Similar to recent studies by Peltzman (2000) and Borenstein et al. (1997) documenting asymmetric responses by traditional brick-and-mortar establishments, we find that online mortgage rates also respond more quickly to increases than to decreases in lenders' cost of funds. Section 4 offers concluding remarks.

This paper represents a first attempt to examine the determinants of firms' decisions to change prices in online markets. Our analysis, based on nearly 10,000 rate quotes from Microsurf (an Internet site that provides comparative information about the mortgage rates offered by different lenders in all 50 states and the District of Columbia), indicates that market structure is an important determinant of lenders' decisions to adjust rates. The answer to the question “Are prices sticky online?” is largely a matter of perspective. On the one hand, while lenders' cost of funds changed on more than 87% of days in our sample, lenders changed their posted mortgage rates only 16% of the time. In addition, the median duration of quoted mortgage rates is between 16.6 and 19.2 days. In this sense, prices appear to be quite rigid in online markets. On the other hand, lenders who changed their rates passed through about 98% of cost changes to consumers within 2 days. In this sense, prices are much less sticky than at traditional retail outlets (see Peltzman, 2000). Thus, the evidence suggests that while firms do not change rates very frequently, those firms that do change rates tend to adjust them rapidly. More importantly, the evidence suggests that online prices are more rigid in concentrated markets. In particular, lenders are about 5% or 6% more likely to change rates in concentrated markets than in more competitive markets. Duration analysis revealed that mortgage rates are between 30% and 40% more durable in concentrated markets. While our finding that rates are less flexible in concentrated markets is consistent with theories of price rigidity, an important puzzles remains: Why is a high degree of price rigidity observed in online mortgage markets, where menu costs and other frictions are virtually zero? Finally, similar to recent studies of conventional markets, we find that online mortgage rates are more responsive to cost increases than cost decreases, with cost increases being passed on to consumers about twice as quickly as cost decreases. While we have provided some speculative arguments regarding factors that might contribute to the observed asymmetries, further theoretical work in this area is needed.