Data frame mutation in R
The fastest way would be,

require(data.table)
data &lt;- data.table(data)
# Remove the percentage from your file and convert the field to numeric.
data[, Profit := as.numeric(gsub("%", "", Profit))]

data
##           Symbol      Date     Time Profit
##  1: BANKNIFTY  4/1/2010  9:55:00  -1.18
##  2: BANKNIFTY  4/1/2010 12:30:00  -2.84
##  3: BANKNIFTY  4/1/2010 12:45:00   7.17
##  4: BANKNIFTY  5/1/2010 11:40:00  -7.11
##  5:      ZEEL 26/6/2012 13:50:00  24.75
##  6:      ZEEL 27/6/2012 15:15:00  -1.90
##  7:      ZEEL 28/6/2012  9:45:00  37.58
##  8:      ZEEL 28/6/2012 14:55:00  23.95
##  9:      ZEEL 29/6/2012 14:20:00  -4.65
## 10:      ZEEL 29/6/2012 14:30:00  -6.01
## 11:      ZEEL 29/6/2012 14:55:00 -12.23
## 12:      ZEEL 29/6/2012 15:15:00  35.13

# Melt the data so that we can easily dcast afterwards.
molten_data &lt;- melt(data[, list(Symbol, Date, Profit)]

# Create a summary by date and Symbol.
dcast(molten_data, id = c("Symbol", "Date")), Date ~ variable + Symbol, fun = sum)

 ##         Date Profit_BANKNIFTY Profit_ZEEL
 ## 1: 26/6/2012             0.00       24.75
 ## 2: 27/6/2012             0.00       -1.90
 ## 3: 28/6/2012             0.00       61.53
 ## 4: 29/6/2012             0.00       12.24
 ## 5:  4/1/2010             3.15        0.00
 ## 6:  5/1/2010            -7.11        0.00