# Load packages
library(tidyverse)
library(tidyquant)
1 Get stock prices and convert to returns
Ra <- c("AAPL", "GOOG", "MSFT") %>%
tq_get(get = "stock.prices",
from = "2026-01-01") %>%
group_by(symbol) %>%
tq_transmute(select = adjusted,
mutate_fun = periodReturn,
period = "monthly",
col_rename = "Ra")
Ra
## # A tibble: 27 × 3
## # Groups: symbol [3]
## symbol date Ra
## <chr> <date> <dbl>
## 1 AAPL 2026-01-30 -0.0425
## 2 AAPL 2026-02-27 0.0191
## 3 AAPL 2026-03-31 -0.0393
## 4 AAPL 2026-04-30 0.0692
## 5 AAPL 2026-05-29 0.151
## 6 AAPL 2026-06-30 -0.0727
## 7 AAPL 2026-07-31 0.0676
## 8 AAPL 2026-08-31 0.0266
## 9 AAPL 2026-09-21 0.0698
## 10 GOOG 2026-01-30 0.0736
## # ℹ 17 more rows
2 Get baseline and convert to returns
Rb <- "^IXIC" %>%
tq_get(get = "stock.prices",
from = "2026-01-01") %>%
tq_transmute(select = adjusted,
mutate_fun = periodReturn,
period = "monthly",
col_rename = "Rb")
Rb
## # A tibble: 9 × 2
## date Rb
## <date> <dbl>
## 1 2026-01-30 0.00973
## 2 2026-02-27 -0.0338
## 3 2026-03-31 -0.0475
## 4 2026-04-30 0.153
## 5 2026-05-29 0.0836
## 6 2026-06-30 -0.0281
## 7 2026-07-31 -0.0320
## 8 2026-08-31 0.0393
## 9 2026-09-21 0.0285
3 Join the two tables
RaRb <- left_join(Ra, Rb, by = c("date" = "date"))
RaRb
## # A tibble: 27 × 4
## # Groups: symbol [3]
## symbol date Ra Rb
## <chr> <date> <dbl> <dbl>
## 1 AAPL 2026-01-30 -0.0425 0.00973
## 2 AAPL 2026-02-27 0.0191 -0.0338
## 3 AAPL 2026-03-31 -0.0393 -0.0475
## 4 AAPL 2026-04-30 0.0692 0.153
## 5 AAPL 2026-05-29 0.151 0.0836
## 6 AAPL 2026-06-30 -0.0727 -0.0281
## 7 AAPL 2026-07-31 0.0676 -0.0320
## 8 AAPL 2026-08-31 0.0266 0.0393
## 9 AAPL 2026-09-21 0.0698 0.0285
## 10 GOOG 2026-01-30 0.0736 0.00973
## # ℹ 17 more rows
4 Calculate CAPM
RaRb_capm <- RaRb %>%
tq_performance(Ra = Ra,
Rb = Rb,
performance_fun = table.CAPM)
RaRb_capm
## # A tibble: 3 × 18
## # Groups: symbol [3]
## symbol ActivePremium Alpha AlphaRobust AnnualizedAlpha Beta `Beta-`
## <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
## 1 AAPL 0.124 0.0154 0.0154 0.201 0.638 0.965
## 2 GOOG -0.0729 -0.011 -0.0098 -0.124 1.55 1.95
## 3 MSFT -0.138 -0.0002 -0.0466 -0.0023 0.776 0.677
## # ℹ 11 more variables: `Beta-Robust` <dbl>, `Beta+` <dbl>, `Beta+Robust` <dbl>,
## # BetaRobust <dbl>, Correlation <dbl>, `Correlationp-value` <dbl>,
## # InformationRatio <dbl>, `R-squared` <dbl>, `R-squaredRobust` <dbl>,
## # TrackingError <dbl>, TreynorRatio <dbl>
Which stock has a positively skewed distribution of returns?
RaRb_capm <- RaRb %>%
tq_performance(Ra = Ra,
Rb = Rb,
performance_fun = SkewnessKurtosisRatio)
RaRb_capm
## # A tibble: 3 × 2
## # Groups: symbol [3]
## symbol SkewnessKurtosisRatio.1
## <chr> <dbl>
## 1 AAPL 0.0747
## 2 GOOG 0.346
## 3 MSFT 0.146